Low-lying continuum states of drip-line oxygen isotopes
NASA Astrophysics Data System (ADS)
Tsukiyama, Koshiroh; Otsuka, Takaharu; Fujimoto, Rintaro
2015-09-01
Low-lying continuum states of exotic oxygen isotopes with A=23-26 are studied, by introducing the continuum-coupled shell model (CCSM) characterized by an infinite wall placed very far away and by an interaction for continuum coupling constructed in a close relation to the realistic shell-model Hamiltonian. Neutron-emission spectra from exotic oxygen isotopes are calculated by the doorway-state approach in heavy-ion multi-nucleon transfer reactions. The results agree with experiment remarkably well, providing evidence that the continuum effects are stronger than ˜ 1 MeV, consistent with the shell evolution in exotic nuclei. The peaks in the neutron spectra are understood as doorway-state resonances. The results by this CCSM doorway-state approach are compared with calculations on neutron-scattering resonance peaks made within the CCSM phase-shift approach and also with those obtained in the Gamow shell model, by taking the same Hamiltonian.
On the low-lying states of TiC
NASA Technical Reports Server (NTRS)
Bauschlicher, C. W., Jr.; Siegbahn, P. E. M.
1984-01-01
The ground and low-lying excited states of TiC are investigated using a CASSCF-externally contracted CI approach. The calculations yield a 3Sigma(+) ground state, but the 1Sigma(+) state is only 780/cm higher and cannot be ruled out. The low-lying states have some triple bond character. The nature of the bonding and origin of the states are discussed.
Low-lying electronic states of carotenoids.
DeCoster, B; Christensen, R L; Gebhard, R; Lugtenburg, J; Farhoosh, R; Frank, H A
1992-08-28
Four all-trans carotenoids, spheroidene, 3,4-dihydrospheroidene, 3,4,5,6-tetrahydrospheroidene, and 3,4,7,8-tetrahydrospheroidene, have been purified using HPLC techniques and analyzed using absorption, fluorescence and fluorescence excitation spectroscopy of room temperature solutions. This series of molecules, for which the extent of pi-electron conjugation decreases from 10 to seven carbon-carbon double bonds, exhibits a systematic crossover from S2----S0 (1(1)Bu----1(1)Ag) to S1----S0 (2(1)Ag----1(1)Ag) emission with decreasing chain length. Extrapolation of the S1----S0 transition energies indicates that the 2(1)Ag states of longer carotenoids have considerably lower energies than previously thought. The energies of the S1 states of spheroidenes and other long carotenoids are correlated with the S1 energies of their chlorophyll partners in antenna complexes of photosynthetic systems. Implications for energy transfer in photosynthetic antenna are discussed. PMID:1510992
Experimental investigation of low-lying states of pionic atoms
Amian, W.B.; Cloth, P.; Djaloeis, A.; Filges, D.; Gotta, D.; Kilian, K.; Machner, H.; Morsch, H.P.; Protic, D.; Riepe, G.; Roderburg, E.; von Rossen, P.; Turek, P.; Watzlawik, K.H. ); Jarczyk, L.; Smyrski, J.; Stralkowski, A. ); Budzanowski, A.; Dabrowski, H.; Skwirczynska, I. ); Plendl, H. ); Konijn, J. )
1991-04-10
We propose to study pionic atoms in low-lying states. The pions will be produced with the help of recoil free kinematics at small energies in the laboratory. A dedicated detector will be applied allowing the measurements of the width as well as the energy shift of these states.
The Low-Lying Electronic States of Mg2(+)
NASA Technical Reports Server (NTRS)
Ricca, Alessandra; Bauschlicher, Charles W., Jr.
1994-01-01
The low-lying doublet and quartet states of Mg+ have been studied using a multireference configuration interaction approach. The effect of inner-shell correlation has been included using the core-polarization potential method. The computed spectroscopic constants, lifetimes, and oscillator strengths should help resolve the difference between the recent experiments and previous theoretical calculations.
Low-lying Collective States in {sup 136}Ba
Scheck, M.; Mukhopadhyay, S.; Crider, B.; Choudry, S. N.; Elhami, E.; Peters, E. E.; McEllistrem, M. T.; Orce, J. N.; Yates, S. W.
2009-01-28
Low-lying collective states in {sup 136}Ba were investigated with (n,n'{gamma}) techniques, including Doppler-shift attenuation lifetime measurements. The level spins, lifetimes, branching ratios, multipole-mixing ratios and transition strengths reveal candidates for symmetric-phonon states up to third order. The 2{sub ms}{sup +} mixed-symmetry state was confirmed as unfragmented and a candidate for a [2{sub 1}{sup +} x 2{sub ms}{sup +}]{sub 3}{sup +} two-phonon mixed-symmetry state is proposed.
Transition properties of low-lying states in atomic indium
Sahoo, B. K.; Das, B. P.
2011-07-15
We present here the results of our relativistic many-body calculations of various properties of the first six low-lying excited states of indium. The calculations were performed using the relativistic coupled-cluster method in the framework of the singles, doubles, and partial triples approximation. The lifetime of the [4p{sup 6}]5s{sup 2}5p{sub 3/2} state in this atom is determined. Our results could be used to shed light on the reliability of the lifetime measurements of the excited states of atomic indium that we have considered in the present work.
On the low lying singlet states of BeO
NASA Technical Reports Server (NTRS)
Bauschlicher, C. W., Jr.; Lengsfield, B. H.; Yarkony, D. R.
1980-01-01
Calculations of the ground and low-lying singlet states of BeO are performed in order to gain an understanding of the techniques needed to treat the excited states of other, more complex, ionic molecules. The MCSCF and CI calculations are based on a Gaussian basis set of slightly better than double zeta plus polarization quality for single configuration descriptions of the states. The calculated X-A and X-B state separations are found to be in agreement with experimental measurements. The 1 Sigma - and 1 Delta states are predicted to lie approximately 40,000 kaysers above the ground state and are identified as the C and D states.The 2 1 Pi state is found to be approximately 15,000 kaysers and the 3 1 Sigma + state is found to be approximately 65,000 kaysers above the ground state.
On the low-lying states of CuO
NASA Technical Reports Server (NTRS)
Bagus, P. S.; Nelin, C. J.; Bauschlicher, C. W., Jr.
1984-01-01
Self consistent field and correlated wave functions have been computed for the ground and for several low-lying states of CuO. The ground state is X(2)PI and the lowest excited state, at approximately 8,000/cm above X(2)PI, is a previously unidentified 2-sigma(+) state. The separation of these states is compared to that for the similar states of KO and is analysed in terms of integrals between orbitals of the separated free ions. A classification of the states of the molecule based on states of Cu(+) and O(-) which leads to a division into manifolds of states arising from Cu(+) 3d(10) and Cu(+) 3d(9) 4s(1) is considered. It is predicted that the state of the 3d(9) 4s(1) manifold are 10,000 to 30,000/cm above the ground state and assign the observed A2-sigma(+) state at 16,500/cm to this manifold.
Low-Lying Electronic States of CuAu.
Alizadeh Sanati, Davood; Andrae, Dirk
2016-07-28
Coinage metal diatomic molecules are building blocks for nanostructured materials, electronic devices, and catalytically or photochemically active systems that are currently receiving lively interest in both fundamental and applied research. The theoretical study presented here elucidates the electronic structure in the ground and several low-lying excited states of the diatomic molecule CuAu that result from the combination of the atoms in their ground states nd(10)(n + 1)s(1 2)S and lowest excited d-hole states nd(9)(n + 1)s(2 2)D (n = 3 for Cu, n = 5 for Au). Full and smooth potential energy curves, obtained at the multireference configuration interaction (MRCI) level of theory, are presented for the complete set of the thus resulting 44 Λ-S terms and 86 Ω terms. Our approach is based on a scalar relativistic description using the Douglas-Kroll-Hess (DKH) Hamiltonian, with subsequent perturbative inclusion of spin-orbit (SO) coupling via the spin-orbit terms of the Breit-Pauli (BP) Hamiltonian. The Ω terms span an energy interval of about 7 eV at the ground state's equilibrium distance. Spectroscopic constants, calculated for all terms, are shown to accurately reproduce the observation for those nine terms that are experimentally known. PMID:27379475
Mitchell, J. P.; Rogachev, G. V.; Johnson, E. D.; Baby, L. T.; Kemper, K. W.; Peplowski, P. N.; Volya, A.; Wiedenhoever, I.; Moro, A. M.
2010-07-15
Excitation functions of elastic and inelastic {sup 7}Be+p scattering were measured in the energy range between 1.6 and 2.8 MeV in the c.m. An R-matrix analysis of the excitation functions provides strong evidence for new positive parity states in {sup 8}B. A new 2{sup +} state at an excitation energy of 2.55 MeV was observed, and a new 0{sup +} state at 1.9 MeV is tentatively suggested. The R-matrix and time-dependent continuum shell model were used in the analysis of the excitation functions. The new results are compared to the calculations of contemporary theoretical models.
Noncollisional excitation of low-lying states in gaseous nebulae
NASA Technical Reports Server (NTRS)
Rubin, Robert H.
1986-01-01
Consideration is given to the effects of processes other than electron collisional excitation on the energy level populations of species of C, N, and O. It is found that dielectronic as well as direct-radiative recombination may contribute significantly and in some cases be the major input to populating the low-lying metastable levels. It is concluded that the most pronounced changes occur when there is a large effective recombination coefficient to a level and when T(e) is low. The most dramatic change among the forbidden lines occurs for the O II forbidden lines.
The Low-Lying Electronic States of LiB
NASA Technical Reports Server (NTRS)
Ricca, Alessandra; Bauschlicher, Charles W., Jr.; Langhoff, Stephen R. (Technical Monitor)
1995-01-01
The spectroscopic constants for the triplet and singlet states of LiB below about 30 000/ cm are determined using an internally contracted multireference configuration interaction approach in conjunction with [6s 5p 3d 2f] atomic natural orbital basis sets. The ground state is (sup 3)Pi as found in previous work. No excited triplet states are found to be ideal for characterizing the ground state; the (1)(sup 3)Sigma(sup -) state has a transition energy that is too small for many experimental approaches and the (2)(sup 3)Pi and (3)(sup 3)Pi states have bond lengths that are significantly longer than the ground state, resulting in transition intensities that are spread out over many vibrational levels of the ground state.
On the low-lying states of TiN
NASA Technical Reports Server (NTRS)
Bauschlicher, C. W., Jr.
1983-01-01
A series of CAS SCF and multi-reference CI calculations are used to describe the lowest states of TiN. The bonding in all states is described as a triple bond involving the Ti 3d orbitals. The system has some ionic character as seen from both population analysis and dipole moment. The origins of the excited states are discussed.
Conformational landscape and low lying excited states of imatinib.
Vinţeler, Emil; Stan, Nicoleta-Florina; Luchian, Raluca; Căinap, Călin; Ramalho, João P Prates; Chiş, Vasile
2015-04-01
The conformational changes of imatinib (IMT) are crucial for understanding the ligand-receptor interaction and its mechanism of action [Agofonov et al. (2014) Nature Struct Mol Biol 21:848-853]. Therefore, here we investigated the free energy conformational landscape of the free IMT base, aiming to describe the three-dimensional structures and energetic stability of its conformers. Forty-five unique conformers, within an energy window of 4.8 kcal mol(-1) were identified by a conformational search in gas-phase, at the B3LYP/6-31G(d) theoretical level. Among these, the 20 most stable, as well as 4 conformers resulting from optimization of experimental structures found in the two known polymorphs of IMT and in the c-Abl complex were further refined using the 6-31+G(d,p) basis set and the polarizable continuum solvation model. The most stable conformers in gas-phase and water exhibit a V-shaped structure. The major difference between the most stable free conformers and the bioactive conformers consists in the relative orientation of the pyrimidine-pyridine groups responsible for hydrogen bonding interactions in the ATP-binding pocket. The ratio of mole fractions corresponding to the two known (α and β) polymorphic forms of IMT was estimated from the calculated thermochemical data, in quantitative agreement with the existing experimental data related to their solubility. The electronic absorption spectrum of this compound was investigated in water and explained based on the theoretical TD-DFT results, considering the Boltzmann population-averaged computed data at CAM-B3LYP/6-31+G(d,p) level of theory for the nine most stable conformers. PMID:25764326
The Low-Lying Electronic States of YCu
NASA Technical Reports Server (NTRS)
Ricca, Alessandra; Bauschlicher, Charles W., Jr.; Langhoff, Stephen R. (Technical Monitor)
1995-01-01
The spectroscopic constants for the singlet and triplet states of YCu below about 15 000 per centimeter are determined using an internally contracted multireference configuration-interaction approach. These calculations are calibrated by studies of fewer states using higher levels of correlation treatment and/or larger basis sets. The computed T(sub e) values and radiative lifetimes are in reasonable agreement with experiment. The calculations confirm the previous experimental assignment for all but one state, where theory helps resolve between two possible assignments.
Scattering of low lying states in the black hole atmosphere
NASA Astrophysics Data System (ADS)
Giribet, Gaston
2016-07-01
We investigate finite α' effects in string theory on a black hole background. By explicitly computing tree-level scattering amplitudes, we confirm a duality between seemingly different states recently conjectured by Giveon, Itzhaki, and Kutasov. We verify that the relevant 3-point functions factorize in such a way that the duality between oscillator and winding states becomes manifest. This leads us to determine the precise normalization of the dual vertex operators, and confirms at the level of the interacting theory the identification of states suggested by the analysis of the spectrum. This result implies a duality between two seemingly distinct mechanisms driving the violation of the string winding number in the black hole atmosphere.
The low-lying electronic states of LiC
NASA Technical Reports Server (NTRS)
Ricca, Alessandra; Bauschlicher, Charles W., Jr.; Langhoff, Stephen R. (Technical Monitor)
1995-01-01
The spectroscopic constants for the doublet and quartet states of LiC below about 30,000/cm are determined using an internally contracted multireference configuration-interaction approach in conjunction with a [6s 5p 3d 2f] atomic natural orbital basis sets. All of the strongly bound states, X(sup 4)(SIGMA)(sup -),(1)(sup 2)(DELTA), (1)(sup 2)(SIGMA)(sup +), and (2)(sup 2) II, very ionic in character. The only bound-bound quartet transition in this energy range is (2)(sup 4)SIGMA(sup -) and Franck-Condon factors, Einstein A values, and lifetimes are reported for this transition.
Radiative Decays of Low-Lying Excited-State Hyperons
Simon Taylor
2000-05-01
The quark wave-functions of the lower-lying excited-state hyperons Lambda(1405), Sigma(1385), and Lambda(1520) are not well understood. For example, the Lambda(1405) may not be a regular three-quark state but a {bar K}N molecule. Several competing models have been proposed, but none have been convincingly eliminated. Measuring radiative decays provides a means of discriminating between the models. The radiative branching of ratios are predicted to be small ({approx}1%), but the radiative widths vary by factors of 2-10 from model to model. The existing experimental data is sparse and inconsistent; moreover, the radiative decay of the Sigma(1385) has never been observed before (except for one event). These lower-lying excited state hypersons were produced in a tagged photon-beam experiment in the CLAS detector at TJNAF in the reaction gamma p {yields} K{sup +} Y* for photon energies from threshold to 2.4 GeV. The radiative branching ration for the Sigma{sup 0}(1385) relative to the Sigma{sup 0}(1385) {yields} Lambda pi{sup 0} channel was measured to be 0.021 {+-} 0.008{sub -0.007}{sup +0.004}, corresponding to a partial width of 640 {+-} 270{sub -220}{sup +130} keV.
Low-lying states of valence-hole nuclei in the 208Pb region
NASA Astrophysics Data System (ADS)
Jiang, H.; Shen, J. J.; Zhao, Y. M.; Arima, A.
2011-04-01
Systematic calculations of low-lying states for Ir, Pt, Au, Hg and Tl isotopes with neutron numbers between 120 and 125 have been performed within the framework of the SDG-pair approximation of the shell model. We employ a monopole and quadrupole pairing plus quadrupole-quadrupole-type interaction with optimized parameters, which are assumed to be constants for nuclei with the same proton number or neutron number. We calculate binding energies of the ground states, low energy level schemes, electric quadrupole and magnetic dipole moments, and E2 transition rates. Our results are reasonably consistent with the available experimental data as well as previous theoretical studies, in particular, for low-lying yrast states. We also demonstrate that low-lying states of nuclei studied here are usually well represented by very simple configurations in collective nucleon-pair basis.
Effects of tensor correlations on low-lying collective states in finite nuclei
Cao Ligang; Sagawa, H.; Colo, G.
2011-03-15
We present a systematic analysis of the effects induced by tensor correlations on low-lying collective states of magic nuclei, by using the fully self-consistent random phase approximation (RPA) model with Skyrme interactions. The role of the tensor correlations is analyzed in detail in the case of quadrupole (2{sup +}) and octupole (3{sup -}) low-lying collective states in {sup 208}Pb. The example of {sup 40}Ca is also discussed, as well as the case of magnetic dipole states (1{sup +}).
Low-lying states of ruthenium isotopes within the nucleon pair approximation
NASA Astrophysics Data System (ADS)
Jiang, H.; Li, B.; Lei, Y.
2016-05-01
Low-lying states of even-even and odd-mass ruthenium isotopes with mass numbers from 95 to 102, including level schemes, electric quadrupole and magnetic dipole moments, and E 2 transition rates, are studied within the framework of the nucleon pair approximation (NPA) of the shell model, by using the phenomenological pairing plus quadrupole interactions. Good agreement is obtained between the calculated results and experimental data. The interesting behaviors of g (J1+) factors versus nuclear spin J (and mass number A ) in even-even Ru-10296 nuclei are analyzed. The dominant configurations of yrast low-lying states in odd-mass Ru-10195 isotopes are discussed in the collective nucleon-pair subspace. The calculated electric quadrupole moments and magnetic moments of low-lying states, many of which have not yet been measured for these nuclei, are useful for future studies.
Low-lying 1- and 2+ states in 124Sn via inelastic scattering of 17O
NASA Astrophysics Data System (ADS)
Pellegri, L.; Bracco, A.; Crespi, F. C. L.
2016-05-01
The γ decay of low-lying 1-and 2+ states up to the neutron separation energy in 124Sn populate by the inelastic scattering of 17O was measured. The Angular distributions were measured both for the γ rays and the scattered 17O ions. The results are presented.
Spectroscopic Properties and Potential Energy Curves of Low-lying electronic States of RuC
Balasubramanian, K; Guo, R
2003-12-22
The RuC molecule has been a challenging species due to the open-shell nature of Ru resulting in a large number of low-lying electronic states. We have carried out state-of-the-art calculations using the complete active space multi-configuration self-consistent field (CASSCF) followed by multireference configuration interaction (MRCI) methods that included up 18 million configurations, in conjunction with relativistic effects. We have computed 29 low-lying electronic states of RuC with different spin multiplicities and spatial symmetries with energy separations less than 38 000 cm{sup -1}. We find two very closely low-lying electronic states for RuC, viz., {sup 1}{Sigma}{sup +} and {sup 3}{Delta} with the {sup 1}{Sigma}{sup +} being stabilized at higher levels of theory. Our computed spectroscopic constants and dipole moments are in good agreement with experiment although we have reported more electronic states than those that have been observed experimentally. Our computations reveal a strongly bound X{sup 1}{Sigma}{sup +} state with a large dipole moment and an energetically close {sup 3}{Delta} state with a smaller dipole moment. Overall our computed spectroscopic constants of the excited states with energy separations less than 18000 cm{sup -1} agree quite well with those of the corresponding observed states.
Low-Lying ππ* States of Heteroaromatic Molecules: A Challenge for Excited State Methods.
Prlj, Antonio; Sandoval-Salinas, María Eugenia; Casanova, David; Jacquemin, Denis; Corminboeuf, Clémence
2016-06-14
The description of low-lying ππ* states of linear acenes by standard electronic structure methods is known to be challenging. Here, we broaden the framework of this problem by considering a set of fused heteroaromatic rings and demonstrate that standard electronic structure methods do not provide a balanced description of the two (typically) lowest singlet state (La and Lb) excitations. While the Lb state is highly sensitive to correlation effects, La suffers from the same drawbacks as charge transfer excitations. We show that the comparison between CIS/CIS(D) can serve as a diagnostic for detecting the two problematic excited states. Standard TD-DFT and even its spin-flip variant lead to inaccurate excitation energies and interstate gaps, with only a double hybrid functional performing somewhat better. The complication inherent to a balanced description of these states is so important that even CC2 and ADC(2) do not necessarily match the ADC(3) reference. PMID:27144975
A theoretical study of the low-lying states of Ti2 and Zr2
NASA Technical Reports Server (NTRS)
Bauschlicher, Charles W., Jr.; Partridge, Harry; Langhoff, Stephen R.; Rosi, Marzio
1991-01-01
The low-lying states of Ti2 and the valence isoelectronic Zr2 are examined theoretically by means of a multireference configuration-interaction (MRCI) method. MRCI calculations demonstrate that two of the Zr2 states are very low-lying and that the resulting vertical excitation is consistent with the optical spectrum of Zr2. The ground state is predicted for Ti2 on the basis of valence correlation with the MRCI method and the average coupled-pair functional technique. Calculations of the inner-shell correlation effects are estimated and found to lower the 3Delta g state to a ground state, and another to a very low-lying state. The ground state of Ti2 is assigned to 3Delta g since it is lower than the other state at all levels of correlation and is derived from the same atomic asymptote. This conclusion is supported by the lack of an electron-spin resonance signal but contradicts the absence of subcomponents on the Raman spectral lines.
New extrapolation method for low-lying states of nuclei in the sd and the pf shells
Shen, J. J.; Zhao, Y. M.; Arima, A.; Yoshinaga, N.
2011-04-15
We study extrapolation approaches to evaluate energies of low-lying states for nuclei in the sd and pf shells, by sorting the diagonal matrix elements of the nuclear shell-model Hamiltonian. We introduce an extrapolation method with perturbation and apply our new method to predict both low-lying state energies and E2 transition rates between low-lying states. Our predicted results arrive at an accuracy of the root-mean-squared deviations {approx}40-60 keV for low-lying states of these nuclei.
Calculations of energy levels and lifetimes of low-lying states of barium and radium
Dzuba, V. A.; Ginges, J. S. M.
2006-03-15
We use the configuration-interaction method and many-body perturbation theory to perform accurate calculations of energy levels, transition amplitudes, and lifetimes of low-lying states of barium and radium. Calculations for radium are needed for the planning of measurements of parity- and time-invariance-violating effects which are strongly enhanced in this atom. Calculations for barium are used to control the accuracy of the calculations.
Computed potential surfaces for six low-lying states of Ni3
NASA Technical Reports Server (NTRS)
Walch, Stephen P.
1987-01-01
Selected portions of the potential surfaces for six low lying states of Ni3 are the subject of the present SCF/CCI calculations using the effective core potentials developed by Hay and Wadt (1985); the four states are studied for near-equilateral triangle geometries are within 0.04 eV of each other. Two states are studied for linear geometries, of which the first is 0.16 eV higher than the corresponding near-equilateral triangle state and the second is estimated to be nearly degenerate with the near-equilateral triangle structures.
Wolf, A.; Zamfir, N.V.; Caprio, M.A.; Berant, Z.; Brenner, D.S.; Pietralla, N.; Gill, R.L.; Casten, R.F.; Beausang, C.W.; Kruecken, R.; Zyromski, K.E.; Barton, C.J.; Cooper, J.R.; Hecht, A.A.; Newman, H.; Novak, J.R.; Cederkall, J.
2002-08-27
A study of the low-lying levels of 128Ba was performed using three clover detectors in a compact arrangement. The decay properties of several low-lying states were investigated, spin assignments were made for two states, and several E2/M1 mixing ratios were determined.
Ozone absorption spectroscopy in search of low-lying electronic states
NASA Technical Reports Server (NTRS)
Anderson, S. M.; Mauersberger, K.
1995-01-01
A spectrometer capable of detecting ozone absorption features 9 orders of magnitude weaker than the Hartley band has been employed to investigate the molecule's near-infrared absorption spectrum. At this sensitivity a wealth of information on the low-lying electronically excited states often believed to play a role in atmospheric chemistry is available in the form of vibrational and rotational structure. We have analyzed these spectra using a combination of digital filtering and isotope substitution and find evidence for three electronically excited states below 1.5 eV. The lowest of these states is metastable, bound by approximately 0.1 eV and probably the (3)A2 rather than the (3)B2 state. Its adiabatic electronic energy is 1.24 +/- 0.01 eV, slightly above the dissociation energy of the ground state. Two higher states, at 1.29 +/- 0.03 and 1.48 +/- 0.03 eV are identified as the (3)B2 and the (3)B1, respectively. Combined with other recent theoretical and experimental data on the low-lying electronic states of ozone, these results imply that these are, in fact, the lowest three excited states; that is, there are no electronically excited states of ozone lying below the energy of O(3P) + O2((3)Sigma(-), v = 0). Some of the implications for atmospheric chemistry are considered.
Regularities of low-lying states with random interactions in the fermion dynamical symmetry model
NASA Astrophysics Data System (ADS)
Fu, G. J.; Zhao, Y. M.; Arima, A.
2014-12-01
In this paper we study low-lying states under random interactions in the framework of the fermion dynamical symmetry model (FDSM), regardless of the ground state spin. Very strong correlations are found for R6 versus R4 (where RI≡EI1+/E21+ ) for the entire ensemble. We present arguments on the origin of these regular patterns in terms of the dynamical symmetries of the FDSM. The regular patterns of B (E 2 ;41+→21+) versus B (E 2 ;21+→01+) are found.
Study of low-lying electronic states of ozone by anion photoelectron spectroscopy of O - 3
NASA Astrophysics Data System (ADS)
Arnold, Don W.; Xu, Cangshan; Kim, Eun H.; Neumark, Daniel M.
1994-07-01
The low-lying electronic states of ozone are studied using anion photoelectron spectroscopy of O-3. The spectra show photodetachment transitions from O-3 to the X˜ 1A1 ground state and to the five lowest lying electronic states of the ozone molecule, namely the 3A2, 3B2, 1A2, 3B1, and 1B1 states. The geometry of the ozonide anion determined from a Franck-Condon analysis of the O3 X 1A1 ground state spectrum agrees reasonably well with previous work. The excited state spectra are dominated by bending vibrational progressions which, for some states, extend well above the dissociation asymptote without noticeable lifetime broadening effects. Preliminary assignments are based upon photoelectron angular distributions and comparison with ab initio calculations. None of the excited states observed lies below the ground state dissociation limit of O3 as suggested by previous experimental and theoretical results.
Theoretical Study of the Low-Lying States of MgN+2
NASA Technical Reports Server (NTRS)
Maitre, Philippe; Bauschlicher, Charles W., Jr.; Gross, Anthony R. (Technical Monitor)
1994-01-01
The structure and binding energies of the low-lying states of MgN2+ have been computed at the multireference configuration interaction level of theory. The effect of Mg inner-shell correlation have been included using the core-polarization potential method. The charge-quadrupole interaction results in a linear 2Sigma+ ground state as expected. The excited states can arise from either the interaction of the 2-P state of Mg+ with N2 or from charge transfer states with Mg(sup 2+)N2- bonding character. The lowest lying excited state, 2-B2, is mixture of these two mechanisms, which results in a C2v, geometry with Mg atoms sitting at the N2 bond midpoint. The small barrier in the bending potential exists between this state and the 2-II State which is the lowest lying linear excited state.
Microscopic structure of low-lying states in {sup 188,190,192}Os
Lo Iudice, N.; Sushkov, A. V.
2008-11-15
The phonon and quasiparticle structure of the low-lying states in {sup 188,190,192}Os is investigated within the microscopic quasiparticle-phonon model. An overall agreement with the data is obtained for energies and transitions. The properties of the 0{sup +} states are found to be correlated with the evolution of the nuclear shape toward the {gamma}-soft region. Special attention is devoted at the 4{sub 3}{sup +} state. This state is found to be composed of a large double-{gamma} phonon component coexisting with an even larger one-phonon hexadecapole piece. Such a mixed phonon structure explains the observed, apparently contradictory, properties of the 4{sub 3}{sup +} states in Os isotopes.
RDDS lifetime measurements of low-lying superdeformed states in {sup 194}Hg
Kuehn, R.; Dewald, A.; Kruecken, R.
1996-12-31
The lifetimes of three low-lying states in the superdeformed (SD) yrast band of {sup 194}Hg were measured by the recoil-distance Doppler-shift method. The deduced transition quadrupole moments, Q{sub t}, equal those extracted from a DSAM measurement for the high-lying states of the band corroborate the assumption that the decay out of SD bands does not strongly affect the structure of the corresponding states. By a simple mixing-model the decay can be described assuming a very small admixture of normal-deformed (ND) states to the decaying SD states. The deduced ND mixing amplitudes for the yrast SD bands in {sup 192,194}Hg and {sup 194}Pb are presented along with average transition quadrupole moments for the lower parts of the excited SD bands.
Spectroscopy of low-lying states in neutron-deficient astatine and francium nuclei
Jakobsson, U. Cederwall, B.; Uusitalo, J.; Auranen, K.; Badran, H.; Cox, D. M.; Grahn, T.; Greenlees, P. T.; Julin, R.; Juutinen, S.; Herzáň, A.; Konki, J.; Leino, M.; Mallaburn, M.; Pakarinen, J.; Papadakis, P.; Partanen, J.; Rahkila, P.; Sandzelius, M.; Sarén, J.; and others
2015-10-15
Low-lying states in neutron-deficient astatine and francium nuclei have been studied by means of in-beam and delayed spectroscopy. The 13/2{sup +} state has been observed in francium nuclei with a similar down-sloping trend as in neighbouring astatine and bismuth isotopes, as a function of decreasing neutron number. A systematic trend can also now be seen for the 1/2{sup +} state both in astatine and francium nuclei, where the level energy decreases steeply as a function of neutron number when moving further away from the neutron shell closure. This trend is very similar between astatine nuclei and their francium isotones. Moreover, shape coexistence has been observed between the 13/2{sup +} state and the spherical 9/2{sup −} ground state in {sup 203}Fr and {sup 205}Fr.
Spectroscopy of low-lying states in neutron-deficient astatine and francium nuclei
NASA Astrophysics Data System (ADS)
Jakobsson, U.; Uusitalo, J.; Auranen, K.; Badran, H.; Cederwall, B.; Cox, D. M.; Grahn, T.; Greenlees, P. T.; Julin, R.; Juutinen, S.; HerzáÅ, A.; Konki, J.; Leino, M.; Mallaburn, M.; Pakarinen, J.; Papadakis, P.; Partanen, J.; Rahkila, P.; Sandzelius, M.; Sarén, J.; Scholey, C.; Sorri, J.; Stolze, S.
2015-10-01
Low-lying states in neutron-deficient astatine and francium nuclei have been studied by means of in-beam and delayed spectroscopy. The 13/2+ state has been observed in francium nuclei with a similar down-sloping trend as in neighbouring astatine and bismuth isotopes, as a function of decreasing neutron number. A systematic trend can also now be seen for the 1/2+ state both in astatine and francium nuclei, where the level energy decreases steeply as a function of neutron number when moving further away from the neutron shell closure. This trend is very similar between astatine nuclei and their francium isotones. Moreover, shape coexistence has been observed between the 13/2+ state and the spherical 9/2- ground state in 203Fr and 205Fr.
Investigation of solvatochromism in the low-lying singlet states of dithienyl polyenes
NASA Astrophysics Data System (ADS)
Cooper, Thomas M.; Natarajan, Lalgudi V.; Sowards, Laura A.; Spangler, Charles W.
1999-09-01
To understand the low-lying singlet states of dithienyl polyenes, we investigated the solvatochromism of a series of α,ω-di(2-dithienyl 3,4-butyl) polyenes having n=1-5 double bonds. Absorption and emission spectra were collected in a series of aprotic solvents. The absorption energy dispersion effect sensitivity increased smoothly with n, reaching asymptotic behavior as n approached 5. The emission energy had less solvent sensitivity. The trends gave evidence for the existence of a 1B∗u absorbing state and a 1A∗g emitting state. We observed sensitivity of the absorbing and emitting states to solute-solvent electrostatic interactions, suggesting the dithienyl polyenes had a polar ground state conformation.
On the low-lying states of MgO. II
NASA Technical Reports Server (NTRS)
Bauschlicher, C. W., Jr.; Lengsfield, B. H., III; Silver, D. M.; Yarkony, D. R.
1981-01-01
Using a double zeta plus polarization basis set of Slater orbitals, full valence MCSCF (FVMCSCF) calculations were performed for the low-lying states of MgO. For each state the FVMCSCF calculations were used to identify the important configurations which are then used in the MCSCF calculation and subsequently as references in a single and double excitation CI calculation. This approach is found to treat all states equivalently, with the maximum error in the computed transition energies and equilibrium bond lengths of 800/cm and approximately 0.03 A, respectively. The b 3 Sigma + state which has yet to be characterized experimentally is predicted to have a transition energy of approximately 8300/cm and a bond length of 1.79 A. A spectroscopic analysis of the potential curves indicates that their shapes are in quite reasonable agreement with the range of experimental results.
Ground and Low-Lying Collective States of Rotating Three-Boson System
NASA Astrophysics Data System (ADS)
Imran, Mohd.; Ahsan, M. A. H.
2016-04-01
The ground and low-lying collective states of a rotating system of N = 3 bosons harmonically confined in quasi-two-dimension and interacting via repulsive finite-range Gaussian potential is studied in weakly to moderately interacting regime. The N-body Hamiltonian matrix is diagonalized in subspaces of quantized total angular momenta 0 ≥ L ≥ 4N to obtain the ground and low-lying eigenstates. Our numerical results show that breathing modes with N-body eigenenergy spacing of 2ħω⊥, known to exist in strictly 2D system with zero-range (δ-function) interaction potential, may as well exist in quasi-2D system with finite-range Gaussian interaction potential. To gain an insight into the many-body states, the von Neumann entropy is calculated as a measure of quantum correlation and the conditional probability distribution is analyzed for the internal structure of the eigenstates. In the rapidly rotating regime the ground state in angular momentum subspaces L = (q/2)N (N ‑ 1) with q = 2, 4 is found to exhibit the anticorrelation structure suggesting that it may variationally be described by a Bose-Laughlin like state. We further observe that the first breathing mode exhibits features similar to the Bose-Laughlin state in having eigenenergy, von Neumann entropy and internal structure independent of interaction for the three-boson system considered here. On the contrary, for eigenstates lying between the Bose-Laughlin like ground state and the first breathing mode, values of eigenenergy, von Neumann entropy and internal structure are found to vary with interaction.
Cluster correlations for low-lying intruder states of 12Be
NASA Astrophysics Data System (ADS)
Ito, M.; Itagaki, N.; Ikeda, K.
2012-01-01
The formation of intruder states in the low-lying states of 12Be=α+α+4N is studied by applying the generalized two-center cluster model, which can optimize the excess neutrons' orbits depending on the α-α distance. The correlation energy for the intruder states is analyzed from the viewpoint of two different pictures based on the cluster structure: the covalent picture around two α clusters and the binary He-cluster picture. In the covalent picture, the binding energy of (π32-)2(σ12+)2, corresponding to ν(0p)4(1s0d)2 in a naive shell model, gains largely owing to the spin-triplet pairing of the 0d-wave neutrons, which is induced by the two-body spin-orbit interaction. The spin-triplet pairing gives rise to the reduction of the kinetic energy and the increase of the attractive spin-orbit interaction for the excess neutrons. As a result of these correlation energies, the ν(0p)4(1s0d)2 configuration becomes dominant in the ground state. In the binary cluster picture, the correlation energy is investigated from the coupled channels among α+8He, 6He+6He, and 5He+7He. The coupling to 5He+7He, which is neglected in usual binary-cluster models, plays an important role for a large reduction of kinetic energy and the formation of a pair of the low-lying 0+ states with a close energy spacing recently observed in experiment. The rotational bands are also discussed from the viewpoint of these two cluster pictures.
Ab initio study of low-lying electronic states of SnCl2+.
Lee, Edmond P F; Dyke, John M; Chow, Wan-ki; Mok, Daniel K W; Chau, Foo-tim
2007-12-20
Complete active space self-consistent field (CASSCF), multireference configuration interaction (MRCI), and restricted-spin coupled-cluster singles-doubles with perturbative triples [RCCSD(T)] calculations have been carried out on low-lying doublet and quartet states of SnCl2+, employing basis sets of up to aug-cc-pV5Z quality. Effects of core correlation and off-diagonal spin-orbit interaction on computed vertical ionization energies were investigated. The best theoretical estimate of the adiabatic ionization energy (including zero-point vibrational energy correction) to the X2A1 state of SnCl2+ is 10.093+/-0.010 eV. The first photoelectron band of SnCl2 has also been simulated by employing RCCSD(T)/aug-cc-pV5Z potential energy functions and including Duschinsky rotation and anharmonicity. PMID:18034464
Low-lying states in 96Nb from the (t,α) reaction
NASA Astrophysics Data System (ADS)
Cloessner, Paul F.; Stöffl, Wolfgang; Sheline, Raymond K.; Lanier, Robert G.
1984-02-01
The nuclear structure of 96Nb has been studied with the (t,α) reaction at 17 MeV on an isotopically enriched target of 97Mo using a quadrupole-three-dipole spectrometer. Measured angular distributions were compared with distorted-wave Born approximation calculations to assign l transfer values. The results are combined with published data and shell model considerations to reassign the 3- state of the low-lying π(p12)1ν(d52)-1 configuration and to confirm the assignments of the spins and parities of the other levels observed. [NUCLEAR REACTIONS 97Mo(t,α)96Nb, Et=17 MeV, enriched target; measured Eα,σ(θ). DWBA analysis. 96Nb deduced levels, Jπ. Compared 96Nb and 92Nb using Pandya relation.
Theoretical study of the low-lying excited states of ABCO, DABCO and homologous cage amines
NASA Astrophysics Data System (ADS)
Galasso, V.
1997-02-01
The electronic spectra of 1-azabicyclo[2.2.2]octane (ABCO), 1,4-diazabicyclo[2.2.2]octane (DABCO), and their [1.1.1] and [3.3.3] congeners have been studied at the ab initio level using the symmetry adapted cluster configuration interaction method. A comprehensive theoretical prediction of the discrete excitation spectra, up to the HOMO → 5s transition, is presented. All the low-lying singlet and triplet electronic states of these symmetric cage amines are found to have essentially Rydberg nature and originate from excitations out of the n-type molecular orbitals. The theoretical results correlate with the available spectroscopic data satisfactorily and provide quantitative support to a number of experimental assignments based on REMPI and MCD measurements.
Regularities in low-lying states of atomic nuclei with random interactions
NASA Astrophysics Data System (ADS)
Fu, G. J.; Shen, J. J.; Zhao, Y. M.; Arima, A.
2015-05-01
In this paper we study low-lying states of atomic nuclei with random interactions, within the framework of the nuclear shell model. The distributions of R6 versus R4 (where RI≡EI1+/E21+ ), empirical proton-neutron interaction, and charge radius are investigated by using a two-body random ensemble. The Mallmann plot exhibits statistical correlations between R6 and R4. The proton-neutron interaction between the last proton and the last neutron in even-A nuclei is found to be stronger than that in odd-A nuclei, and that in N =Z nuclei is even stronger. Simple relations of nuclear charge radii for neighboring nuclei are found to survive remarkably for the random ensemble.
Properties of the low-lying electronic states of phenanthrene: Exact PPP results
Chakrabarti, A.; Ramasesha, S.
1996-10-05
The authors report properties of the exact low-lying states of phenanthrene, its anion and dianion within the Pariser-Parr-Pople (PPP) model. The experimentally known singlet states of the neutral molecule are well reproduced by the model. The intensities for one and two photon absorption to various single states are also in good agreement with experiment. From the bond orders of these states, the authors predict the equilibrium geometries. The relaxation energies of these states, computed from charge-charge correlations and bond orders, are presented. The authors also present results of ring current calculations in the singlet ground state of phenanthrene. The authors have also reported energies, spin densities, bond orders, and relaxation energies of several triplet states and compared then with experiments as well as with other calculations, where available. The fine structure constants D and E, computed in the lowest triplet state, compare well with those obtained from experiments. These properties are also presented for the anions and the dianions. The PPP model in these cases predicts a low-energy (< 1 eV) dipole excitation. 31 refs., 4 figs., 9 tabs.
Low-lying electronic states of LiF molecule with inner electrons correlation
NASA Astrophysics Data System (ADS)
Wan, Ming-jie; Huang, Duo-hui; Yang, Jun-sheng; Cao, Qi-long; Jin, Cheng-guo; Wang, Fan-hou
2015-06-01
The potential energy curves and dipole moments of the low-lying electronic states of LiF molecule are performed by using highly accurate multi-reference configuration interaction with Awcv5z basis sets. 1s, the inner shell of Li is considered as the closed orbit, which is used to characterise the spectroscopic properties of a manifold of singlet and triplet states. 16 electronic states correlate with two lowest dissociation channels Li(2S)+F(2P) and Li(2P)+F(2P) are investigated. Spectroscopic parameters of the ground state X1Σ+ have been evaluated and critically compared with the available experimental values and the other theoretical data. However, spectroscopic parameters of 13Π, 11Δ, 11Σ-, 11Π, 13Σ+, 23Σ+, 13Δ, 13Σ-, 23Π, 21Π, 33Π, 31Π and 33Σ+ states are studied for the first time. These 13 excited states have shallow potential wells, and the dispersion coefficients of these excited states are predicted. In additional, oscillator strengths of excited states at equilibrium distances are also predicted.
A theoretical study on low-lying electronic states and spectroscopic properties of PH
NASA Astrophysics Data System (ADS)
Gao, Yufeng; Gao, Tao
2014-01-01
The low-lying electronic states (X3∑-, a1Δ, b1Σ+, A3Π, c1Π and 5∑-) of the PH species correlating with the first three dissociation channels have been investigated at the MRCI + Q/aug-cc-PV5Z level of theory. Accurate adiabatic potential energy curves and spectroscopic constants (Te, Re, ωeχe, ωe, Be, De) of these electronic states have been reported. Effect of the spin-orbit coupling on the A3Π and 5∑- states of the PH has been calculated, which lead to the spin-orbit-induced predissociation of the A3Π state. Electronic transition moment, Einstein coefficients and Franck-Condon factors for the A3Π - X3∑- system have been calculated. Dipole moment functions (μe) and radiative lifetime (τv‧) for the A3Π state has also been determined. The radiative lifetime for A3Π - X3∑- transition is computed and compared with the available data.
Potential energy curves for the ground and low-lying excited states of CuAg
Alizadeh, Davood; Shayesteh, Alireza E-mail: ashayesteh@ut.ac.ir; Jamshidi, Zahra E-mail: ashayesteh@ut.ac.ir
2014-10-21
The ground and low-lying excited states of heteronuclear diatomic CuAg are examined by multi-reference configuration interaction (MRCI) method. Relativistic effects were treated and probed in two steps. Scalar terms were considered using the spin-free DKH Hamiltonian as a priori and spin-orbit coupling was calculated perturbatively via the spin-orbit terms of the Breit-Pauli Hamiltonian based on MRCI wavefunctions. Potential energy curves of the spin-free states and their corresponding Ω components correlating with the separated atom limits {sup 2}S(Cu) + {sup 2}S(Ag) and {sup 2}D(Cu) + {sup 2}S(Ag) are obtained. The results are in fine agreement with the experimental measurements and tentative conclusions for the ion-pair B0{sup +} state are confirmed by our theoretical calculations. Illustrative results are presented to reveal the relative importance and magnitude of the scalar and spin-orbit effects on the spectroscopic properties of this molecule. Time dependent density functional theory calculations, using the LDA, BLYP, B3LYP, and SAOP functionals have been carried out for CuAg and the accuracy of TD-DFT has been compared with ab initio results.
The low-lying electronic states of pentacene and their roles in singlet fission.
Zeng, Tao; Hoffmann, Roald; Ananth, Nandini
2014-04-16
We present a detailed study of pentacene monomer and dimer that serves to reconcile extant views of its singlet fission. We obtain the correct ordering of singlet excited-state energy levels in a pentacene molecule (E (S1) < E (D)) from multireference calculations with an appropriate active orbital space and dynamical correlation being incorporated. In order to understand the mechanism of singlet fission in pentacene, we use a well-developed diabatization scheme to characterize the six low-lying singlet states of a pentacene dimer that approximates the unit cell structure of crystalline pentacene. The local, single-excitonic diabats are not directly coupled with the important multiexcitonic state but rather mix through their mutual couplings with one of the charge-transfer configurations. We analyze the mixing of diabats as a function of monomer separation and pentacene rotation. By defining an oscillator strength measure of the coherent population of the multiexcitonic diabat, essential to singlet fission, we find this population can, in principle, be increased by small compression along a specific crystal direction. PMID:24697685
Pauli blocking in the low-lying, low-spin states of {sup 141}Pr
Scheck, M.; Choudry, S. N.; Elhami, E.; McEllistrem, M. T.; Mukhopadhyay, S.; Orce, J. N.; Yates, S. W.
2008-09-15
The low-lying, low-spin levels of {sup 141}Pr were investigated using (n,n{sup '}{gamma}) techniques. Level energies, branching ratios, and tentative spin assignments for more than 100 states, linked by nearly 300 transitions, were obtained from two angular distributions (E{sub n}=2.0 and 3.0 MeV) and an excitation function measurement (E{sub n}=1.5-3.2 MeV). The application of the Doppler-shift attenuation method led to the determination of lifetimes. The obtained spectroscopic data provide insight into the wave functions of the states observed. A detailed analysis of the [2{sub 1}{sup +} x d{sub 5/2}] and [2{sub 1}{sup +} x g{sub 7/2}] multiplets provides the first quantitative evidence for Pauli blocking in a spherical odd-mass nucleus. The unpaired particle is used to probe the microscopic structure of the first 2{sup +} state of the adjacent core nuclei {sup 140}Ce and {sup 142}Nd.
Barborini, Matteo; Sorella, Sandro; Guidoni, Leonardo
2014-01-01
We present full structural optimizations of the ground state and of the low lying triplet state of the ethylene molecule by means of Quantum Monte Carlo methods. Using the efficient structural optimization method based on renormalization techniques and on adjoint differentiation algorithms recently proposed [Sorella, S.; Capriotti, L. J. Chem. Phys. 2010, 133, 234111], we present the variational convergence of both wave function parameters and atomic positions. All of the calculations were done using an accurate and compact wave function based on Pauling’s resonating valence bond representation: the Jastrow Antisymmetrized Geminal Power (JAGP). All structural and wave function parameters are optimized, including coefficients and exponents of the Gaussian primitives of the AGP and the Jastrow atomic orbitals. Bond lengths and bond angles are calculated with a statistical error of about 0.1% and are in good agreement with the available experimental data. The Variational and Diffusion Monte Carlo calculations estimate vertical and adiabatic excitation energies in the ranges 4.623(10)–4.688(5) eV and 3.001(5)–3.091(5) eV, respectively. The adiabatic gap, which is in line with other correlated quantum chemistry methods, is slightly higher than the value estimated by recent photodissociation experiments. Our results demonstrate how Quantum Monte Carlo calculations have become a promising and computationally affordable tool for the structural optimization of correlated molecular systems. PMID:24634617
Theoretical calculation of low-lying states of NaAr and NaXe
NASA Technical Reports Server (NTRS)
Laskowski, B. C.; Langhoff, S. R.; Stallcop, J. R.
1981-01-01
Potential curves as well as dipole moments and linking transition moments are calculated for the ground X 2 Sigma + and low lying excited A 2 Pi, B 2 Sigma +, C 2 Sigma +, (4) 2 Sigma +, (2) 2 Pi and (1) 2 Delta states of NaAr and NaXe. Calculations are performed using a self-consistent field plus configuration-interaction procedure with the core electrons replaced by an ab initio effective core potential. The potential curves obtained are found to be considerably less repulsive than the semiempirical curves of Pascale and Vandeplanque (1974) and to agree well with existing experimental data, although the binding energies of those states having potential minima due to van der Waals interactions are underestimated. Emission bands are also calculated for the X 2 Sigma + - C 2 Sigma + excimer transitions of NaAr and NaXe using the calculated transition moments and potential curves, and shown to agree well with experiment on the short-wavelength side of the maximum.
Structure and spectroscopic properties of low-lying states of the HOC(O)O radical.
Linguerri, Roberto; Puzzarini, Cristina; Francisco, Joseph S
2016-02-28
The HOC(O)O radical is a product of the reaction of HOCO radicals with oxygen atoms. The present study provides theoretical prediction of critical spectroscopic features of this radical that should aid in its experimental characterization. Energies, structures, rotational constants, and harmonic frequencies are presented for the ground and two low-lying excited electronic states of HOC(O)O. The energies for the Ã(2)A(″)←X̃(2)A(') and B̃(2)A(')←X̃(2)A(') electronic transitions are reported. The band origin of the B̃←X̃ transition of HOC(O)O is predicted to occur in the near infrared region of the spectrum at around 1.5 eV and it is suggested to be the most promising one for observing this radical spectroscopically. The structural and spectroscopic similarities between HOC(O)O and the isoelectronic radical FC(O)O are discussed. The abundance of experimental data on the FC(O)O radical should guide the spectroscopic characterization of HOC(O)O and serve as a benchmark for the structural and spectroscopic parameters obtained from theory. PMID:26931701
Low-Lying S-States of Two-Electron Systems
NASA Astrophysics Data System (ADS)
Khan, Md. Abdul
2014-04-01
The energies of the low-lying bound S-states of some two-electron systems (treating them as three-body systems) like negatively charged hydrogen, neutral helium, positively charged-lithium, beryllium, carbon, oxygen, neon, argon and negatively charged muonium and exotic positronium ions have been calculated employing hyperspherical harmonics expansion method. The matrix elements of two-body interactions involve Raynal-Revai coefficients which are particularly essential for the numerical solution of three-body Schrődinger equation when the two-body potentials are other from Coulomb or harmonic. The technique has been applied for to two-electron ions 1H- (Z = 1) to 40Ar16+ (Z = 18), negatively charged-muonium Mu- and exotic positronium ion Ps-(e + e - e -) considering purely Coulomb interaction. The available computer facility restricted reliable calculations up to 28 partial waves (i.e. K m = 28) and energies for higher K m have been obtained by applying an extrapolation scheme suggested by Schneider.
Two-photon excitation of low-lying electronic quadrupole states in atomic clusters
Nesterenko, V. O.; Reinhard, P.-G.; Halfmann, T.; Pavlov, L. I.
2006-02-15
A simple scheme of population and detection of low-lying electronic quadrupole modes in free small deformed metal clusters is proposed. The scheme is analyzed in terms of the time-dependent local density approximation calculations. As a test case, the deformed cluster Na{sub 11}{sup +} is considered. Long-living quadrupole oscillations are generated via resonant two-photon (two-dipole) excitation and then detected through the appearance of satellites in the photoelectron spectra generated by a probe pulse. Femtosecond pump and probe pulses with intensities I=2x10{sup 10}-2x10{sup 11} W/cm{sup 2} and pulse duration T=200-500 fs are found to be optimal. The modes of interest are dominated by a single electron-hole pair and so their energies, being combined with the photoelectron data for hole states, allow us to gather full mean-field spectra of valence electrons near the Fermi energy. Besides, the scheme allows us to estimate the lifetime of electron-hole pairs and hence the relaxation time of electronic energy into ionic heat.
Theoretical spectroscopic constants for the low-lying states of the oxides and sulfides of Mo and Tc
NASA Technical Reports Server (NTRS)
Langhoff, Stephen R.; Bauschlicher, Charles W., Jr.; Pettersson, Lars G. M.; Siegbahn, Per E. M.
1989-01-01
Spectroscopic results were determined for the ground and low-lying states of the oxides and sulfides of Mo and Tc, using the single-reference-based modified coupled pair functional method of Ahlrichs et al. (1985) and Chong et al. (1986) and the multireference-based state-averaged CASSCF/MRCI method. Spectroscopic constants, dipole moments, Mulliken populations, and radiative lifetimes were calculated for selected low-lying states of these molecular systems. The spectroscopy of the MoS and TcS molecules was found to be quite analogous to the corresponding oxides.
Theoretical studies of the low-lying states of ScO, ScS, VO, and VS
NASA Technical Reports Server (NTRS)
Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.
1986-01-01
Bonding in the low-lying states of ScO, ScS, VO, and VS is theoretically studied. Excellent agreement is obtained with experimental spectroscopic constants for the low-lying states of ScO and VO. The results for VS and ScS show that the bonding in the oxides and sulfides is similar, but that the smaller electronegativity in S leads to a smaller ionic component in the bonding. The computed D0 of the sulfides are about 86 percent of the corresponding oxides, and the low-lying excited states are lower in the sulfides than in the corresponding oxides. The CPF method is shown to be an accurate and cost-effective method for obtaining reliable spectroscopic constants for these systems.
Fourier Transform Emission Spectroscopy of the Low-Lying Electronic States of NbN
NASA Astrophysics Data System (ADS)
Ram, R. S.; Bernath, P. F.
2000-06-01
The high-resolution spectrum of NbN has been investigated in emission in the 3000-15 000 cm-1 region using a Fourier transform spectrometer. The bands were excited in a microwave discharge through a mixture of NbCl5 vapor, ∼5 mTorr of N2, and 3 Torr of He. Numerous bands observed in the near-infrared region have been classified into the following transitions: f1Φ-c1Γ, e1Π-a1Δ, C3Π0+-A3Σ-1, C3Π0--A3Σ-1, C3Π1-a1Δ, C3Π1-A3Σ-0, d1Σ+-A3Σ-0, and d1Σ+-b1Σ+. These observations are consistent with the energy level diagram provided by laser excitation and emission spectroscopy [Y. Azuma, G. Huang, M. P. J. Lyne, A. J. Merer, and V. I. Srdanov, J. Chem. Phys. 100, 4138-4155 (1993)]. The missing d1Σ+ state has been observed for the first time and its spectroscopic parameters are consistent with the theoretical predictions of S. R. Langhoff and W. Bauschlicher, Jr. [J. Mol. Spectrosc. 143, 169-179 (1990)]. Rotational analysis of a number of bands has been obtained and improved spectroscopic parameters have been extracted for the low-lying electronic states. The observation of several vibrational bands with v = 1 has enabled us to determine the vibrational intervals and equilibrium bond lengths for the A3Σ-0, a1Δ, b1Σ+, d1Σ+, and C3Π1 states.
Taming the low-lying electronic states of FeH.
DeYonker, Nathan J; Allen, Wesley D
2012-12-21
The low-lying electronic states (X (4)Δ, A (4)Π, a (6)Δ, b (6)Π) of the iron monohydride radical, which are especially troublesome for electronic structure theory, have been successfully described using a focal point analysis (FPA) approach that conjoined a correlation-consistent family of basis sets up to aug-cc-pwCV5Z-DK with high-order coupled cluster theory through hextuple (CCSDTQPH) excitations. Adiabatic excitation energies (T(0)) and spectroscopic constants (r(e), r(0), B(e), B(0), D(e), ω(e), v(0), α(e), ω(e)x(e)) were extrapolated to the valence complete basis set Douglas-Kroll (DK) aug-cc-pwCV∞Z-DK CCSDT level of theory, and additional treatments accounted for higher-order valence electron correlation, core correlation, spin-orbit coupling, and the diagonal Born-Oppenheimer correction. The purely ab initio FPA approach yields the following T(0) results (in eV) for the lowest spin-orbit components of each electronic state: 0 (X (4)Δ) < 0.132 (A (4)Π) < 0.190 (a (6)Δ) < 0.444 (b (6)Π). The computed anharmonic fundamental vibrational frequencies (v(0)) for the (4,6)Δ electronic states are within 3 cm(-1) of experiment and provide reliable predictions for the (4,6)Π states. With the cc-pVDZ basis set, even CCSDTQPH energies give an incorrect ground state of FeH, highlighting the importance of combining high-order electron correlation treatments with robust basis sets when studying transition-metal radicals. The FPA computations provide D(0) = 1.86 eV (42.9 kcal mol(-1)) for the 0 K dissociation energy of FeH and Δ(f)H(298) (∘) [FeH((g))] = 107.7 kcal mol(-1) for the enthalpy of formation at room temperature. Despite sizable multireference character in the quartet states, high-order single-reference coupled cluster computations improve the spectroscopic parameters over previous multireference theoretical studies; for example, the X (4)Δ → A (4)Π and a (6)Δ → b (6)Π transition energies are reproduced to 0
The low-lying 2-sigma-minus states of OH
NASA Technical Reports Server (NTRS)
Van Dishoeck, E. F.; Langhoff, S. R.; Dalgarno, A.
1983-01-01
The configuration-interaction method is used to determine the electronic wave functions of the two lowest 2-sigma-minus states of OH using four different atomic orbital basis sets. Potential energy curves, transition moments, oscillator strengths, and photodissociation cross sections are obtained. Electronic transition dipole moments connecting the excited 1 2-sigma-minus and 2(D)2-sigma-minus states with each other and with the ground chi-2-pi state are presented as functions of internuclear distance. The theoretical absorption oscillator strengths for the D-2-sigma-minus(v prime = 0) from chi-2-pi(v double prime = 0) transition are in good agreement with the empirical value derived from astronomical measurement. The photodissociation cross sections for absorption from the v prime = 0, 1, and 2 levels of the ground state into the continuum of the 1 2-sigma-minus state are calculated, and the interstellar and cometary photodissociation rates are derived.
Novel triaxial structure in low-lying states of neutron-rich nuclei around A ≈100
NASA Astrophysics Data System (ADS)
Xiang, J.; Yao, J. M.; Fu, Y.; Wang, Z. H.; Li, Z. P.; Long, W. H.
2016-05-01
Background: In recent years, the study of triaxiality in the low-lying states of atomic nuclei with transition character or shape coexistence has been of great interest. Previous studies indicate that the neutron-rich nuclei in the A ˜100 mass region with Z ˜40 ,N ˜60 serve as good grounds for examining the role of triaxiality in nuclear low-lying states. Purpose: The aim of this work is to provide a microscopic study of low-lying states for nuclei in the A ˜100 mass regions and to examine in detail the role of triaxiality in the shape-coexistence phenomena and the variation of shape with the isospin and spin values at the beyond mean-field level. Method: The starting point of our method is a set of relativistic mean-field plus BCS wave functions generated with a constraint on triaxial deformations (β ,γ ) . The excitation energies and electric multipole transition strengths of low-lying states are calculated by solving a five-dimensional collective Hamiltonian (5DCH) with parameters determined by the mean-field wave functions. Results: The low-lying states of Mo isotopes and of N =60 isotones in the A ˜100 mass region are calculated. The results indicate that triaxiality is essential to reproduce the data of excitation energies and electric quadrupole transition strengths in low-lying states and plays an important role in the shape evolution as a function of nucleon number. However, the decrease of nuclear collectivity with the increase of angular momentum in neutron-rich Mo isotopes has not been reproduced. Conclusions: The evolution of nuclear collectivity in the low-lying states of neutron-rich nuclei in the A ˜100 mass region as a function of nucleon number is governed by the novel triaxial structure. However, the mechanism that governs the variation of nuclear shape with spin in Mo isotopes remains unclear and deserves further investigation by taking into account the effects other than the collective motions.
Das, Mousumi
2014-03-28
We studied the nature of the ground state and low-lying excited states of armchair polyacene oligomers (Polyphenanthrene) within long-range Pariser-Parr-Pople model Hamiltonian with up to 14 monomers using symmetrized density matrix renormalization group technique. The ground state of all armchair polyacenes studied is found to be singlet. The results show that lowest singlet dipole allowed excited state has higher energy for armchair polyacenes as compared to linear fused polyacenes. Moreover, unlike linear fused polyacenes, the lowest singlet excited state of these oligomers is always found to lie below the lowest dipole forbidden two-photon state indicating that these armchair polyacene oligomers strongly fluoresce. The calculations of low-lying excitations on singly and triply electron doped armchair polyacene oligomers show a low energy band with strong transition dipole moment that coupled to charge conductivity. This implies armchair polyacene posses novel field-effect transistor properties. PMID:24697451
Das, Mousumi
2014-03-28
We studied the nature of the ground state and low-lying excited states of armchair polyacene oligomers (Polyphenanthrene) within long-range Pariser-Parr-Pople model Hamiltonian with up to 14 monomers using symmetrized density matrix renormalization group technique. The ground state of all armchair polyacenes studied is found to be singlet. The results show that lowest singlet dipole allowed excited state has higher energy for armchair polyacenes as compared to linear fused polyacenes. Moreover, unlike linear fused polyacenes, the lowest singlet excited state of these oligomers is always found to lie below the lowest dipole forbidden two-photon state indicating that these armchair polyacene oligomers strongly fluoresce. The calculations of low-lying excitations on singly and triply electron doped armchair polyacene oligomers show a low energy band with strong transition dipole moment that coupled to charge conductivity. This implies armchair polyacene posses novel field-effect transistor properties.
Dixit, Gopal; Majumder, Sonjoy; Sahoo, Bijaya K.; Chaudhuri, Rajat K.
2007-10-15
We report electric quadrupole (E2) and magnetic dipole (M1) transition amplitudes of the first few low-lying states of quadruply ionized vanadium (V{sup 4+}), which are important in various experimental applications and astrophysics. To our knowledge, most of these presented results are determined for the first time in the literature. A relativistic multireference Fock-space coupled-cluster theory with single (S), double (D), and partial triple (T) excitations is employed to compute the forbidden transition probabilities and lifetimes of the low-lying states in V{sup 4+}. Estimations of different correlation effects arising through the above formalism have been highlighted by investigating core and valence electron excitations. A long lifetime is found for the first excited 3d {sup 2}D{sub 5/2} state, which suggests that V{sup 4+} may be one of the useful candidates for many important studies.
On the low-lying states of WO - A comparison with CrO and MoO
NASA Technical Reports Server (NTRS)
Nelin, C. J.; Bauschlicher, C. W., Jr.
1985-01-01
The four low-lying states of WO were investigated and compared with similar states of CrO and MoO. For all these systems the ground state is 5 Pi, but the ordering of the upper states is different between WO and either CrO or MoO. The difference in the state ordering arises in part from the fact that in WO all of the states are formed from W(+) in a d4S1 configuration, whereas in both CrO and MoO some states are formed from the d5 configuration and others from the d4S1 configuration.
NASA Technical Reports Server (NTRS)
Langhoff, Stephen R.; Pettersson, Lars G. M.; Bauschlicher, Charles W., Jr.; Partridge, Harry
1987-01-01
A systematic analysis of the low-lying states of all of the second-row transition metal (TM) hydrides except CdH is reported. The calculations included the dominant relativistic contributions through the use of the relativistic effective core potentials of Hay and Wadt (1985). Electron correlation was incorporated, using single-plus-double configuration interaction, the coupled pair functional (CPF) formalism of Ahlrichs et al. (1985), and the Chong and Langhoff (1986) modified version of the CPF method. The spectroscopic parameters D(e), r(e), and mu(e) determined for the low-lying states are compared with the available experimental data and previous theoretical results. In contrast to the first-row TM hydrides studied earlier (Chong et al., 1986), the spectroscopic constants for the second-row TM hydrides were found to be much less sensitive to the level of correlation treatment.
Electron-impact excitation of the low-lying electronic states of HCN
NASA Technical Reports Server (NTRS)
Chutjian, A.; Tanaka, H.; Srivastava, S. K.; Wicke, B. G.
1977-01-01
The first study of the low-energy electron-impact excitation of low-lying electronic transitions in the HCN molecule is reported. Measurements were made at incident electron energies of 11.6 and 21.6 eV in the energy-loss range of 3-10 eV, and at scattering angles of 20-130 deg. Inelastic scattering spectra were placed on the absolute cross-section scale by determining first the ratio of inelastic-to-elastic scattering cross sections, and then separately measuring the absolute elastic scattering cross section. Several new electronic transitions are observed which are intrinsically overlapped in the molecule itself. Assignments of these electronic transitions are suggested. These assignments are based on present spectroscopic and cross-sections measurements, high-energy electron scattering spectra, optical absorption spectra, and ab initio molecular orbital calculations.
Ab initio study of the low lying electronic states of ZnF and ZnF-.
Hayashi, Shinsuke; Léonard, Céline; Chambaud, Gilberte
2008-07-28
Highly correlated ab initio calculations have been performed for an accurate determination of the electronic structure and of the spectroscopy of the low lying electronic states of the ZnF system. Using effective core pseudopotentials and aug-cc-pVQZ basis sets for both atoms, the potential curves, the dipole moment functions, and the transition dipole moments between relevant electronic states have been calculated at the multireference-configuration-interaction level. The spectroscopic constants calculated for the X(2)Sigma(+) ground state are in good agreement with the most recent theoretical and experimental values. It is shown that, besides the X(2)Sigma(+) ground state, the B(2)Sigma(+), the C(2)Pi, and the D(2)Sigma(+) states are bound. The A(2)Pi state, which has been mentioned in previous works, is not bound but its potential presents a shoulder in the Franck-Condon region of the X(2)Sigma(+) ground state. All of the low lying quartet states are found to be repulsive. The absorption transitions from the v=0 level of the X(2)Sigma(+) ground state toward the three bound states have been evaluated and the spectra are presented. The potential energy of the ZnF(-) molecular anion has been determined in the vicinity of its equilibrium geometry and the electronic affinity of ZnF (EA=1.843 eV with the zero energy point correction) has been calculated in agreement with the photoelectron spectroscopy experiments. PMID:18681652
NASA Astrophysics Data System (ADS)
Kerkines, Ioannis S. K.; Mavridis, Aristides
2004-01-01
The ground and low-lying states of the monopositive vanadium and chromium carbides, VC+ and CrC+ have been studied by multireference methods and quantitative basis sets. Potential energy curves for 17 (VC+) and 19 (CrC+) states have been fully calculated. A variety of binding modes is revealed in the low-lying spectrum of the two molecular cations, often accompanied with an electronic charge transfer from the metal cation towards carbon. Two states compete for the ground state identity in both systems. One state comprises two π and ½σ bonds (similarly to ScC+ and TiC+), while the other state forms a genuine triple bond. After a rather intricate analysis including core electron effects, scalar relativity and curve shifts, the formal ground states of VC+ and CrC+ are found to be of 3Δ and 2Δ symmetry, with estimated energy differences from the competing 1Σ+ and 4Σ- states of 1-3 and 3-7 kcal/mol, respectively. At the highest level of theory including core/valence correlation and one-electron relativistic effects, the calculated ground-state binding energies are in satisfactory agreement with available experimental values.
An investigation into low-lying electronic states of HCS{sub 2} via threshold photoelectron imaging
Qin, Zhengbo; Cong, Ran; Liu, Zhiling; Xie, Hua; Tang, Zichao E-mail: fanhj@dicp.ac.cn; Fan, Hongjun E-mail: fanhj@dicp.ac.cn
2014-06-07
Low-energy photoelectron imaging spectra of HCS{sub 2}{sup −} are reported for the first time. Vibrationally resolved photodetachment transitions from the ground state of HCS{sub 2}{sup −} to the ground state and low-lying excited states of HCS{sub 2} are observed. Combined with the ab intio calculations and Franck-Condon simulations, well-resolved vibrational spectra demonstrate definitive evidence for the resolution of the ground-state and excited states of HCS{sub 2} radical in the gaseous phase. The ground state and two low-lying excited states of HCS{sub 2} radical are assigned as {sup 2}B{sub 2}, {sup 2}A{sub 2}, and {sup 2}A{sub 1} states, respectively. The adiabatic electron affinity is determined to be 2.910 ± 0.007 eV. And the term energies of the excited states, T{sub 0} = 0.451 ± 0.009 eV and 0.553 ± 0.009 eV, are directly measured from the experimental data, respectively. Angular filtering photoelectron spectra are carried out to assist in the spectral band assignment.
Hauschild, K.; Bernstein, L.A.; Becker, J.A.
1996-12-31
The observation of one-step `primary` gamma-ray transitions directly linking the superdeformed (SD) states to the normal deformed (ND) low-lying states of known excitation energies (E{sub x}), spins and parities (J{sup {pi}}) is crucial to determining the E{sub x} and J{sup {pi}} of the SD states. With this knowledge one can begin to address some of the outstanding problems associated with SD nuclei, such as the identical band issue, and one can also place more stringent restrictions on theoretical calculations which predict SD states and their properties. Brinkman, et al., used the early implementation of the GAMMASPHERE spectrometer array (32 detectors) and proposed a single, candidate {gamma} ray linking the {sup 194}Pb yrast SD band to the low-lying ND states in {sup 194}Pb. Using 55 detectors in the GAMMASPHERE array Khoo, et al., observed multiple links between the yrast SD band in {sup 194}Hg and the low-lying level scheme and conclusively determined E{sub x} and J of the yrast SD states. Here the authors report on an experiment in which Gammasphere with 88 detectors was used and the E{sub x} and J{sup {pi}} values of the yrast SD states in {sup 194}Pb were uniquely determined. Twelve one-step linking transitions between the yrast SD band and low-lying states in {sup 194}Pb have been identified, including the transition proposed by Brinkman. These transitions have been placed in the level scheme of {sup 194}Pb using coincidence relationships and agreements between the energies of the primary transitions and the energy differences in level spacings. Furthermore, measurements of angular asymmetries have yielded the multipolarities of the primaries which have allowed J{sup {pi}} assignments of the {sup 194}Pb SD states to be unambiguously determined for the first time without a priori assumptions about the character of SD bands. A study performed in parallel to this work using the EUROGAM-II array reports similar, but somewhat less extensive, results.
Algebraic approach to the structure of the low-lying states in A ≈100 Ru isotopes
NASA Astrophysics Data System (ADS)
Kisyov, S.; Bucurescu, D.; Jolie, J.; Lalkovski, S.
2016-04-01
The structure of the low-lying states in the odd- and even-mass A ≈100 Ru isotopes is studied in the framework of two algebraic models. The even-mass Ru nuclei are first described within the interacting boson model 1 (IBM-1). The output of these calculations was then used to calculate the odd-A isotopes within the interacting boson-fermion model 1 (IBFM-1), where a coupling of the odd neutron to the even-even core is considered. The level energies and transition probabilities calculated in the present work are tested against the experimental data. One-nucleon transfer spectroscopic factors as well as electromagnetic moments were also calculated for the odd-A Ru and compared to the experimental values. The transitional character of the isotopes is studied. Most of the low-lying positive-parity states in the odd-A Ru nuclei below 2 MeV are interpreted on the basis of ν d5 /2 and ν g7 /2 configurations. The role of the ν s1 /2 orbital in the nuclear structure of the odd-mass Ru nuclei at low energies is also studied. The negative-parity states are interpreted as ν h11 /2 excitations coupled to the core. The evolution of the IBM-1 and IBFM-1 parameters is discussed.
Theoretical spectroscopy study of the low-lying electronic states of UX and UX+, X = F and Cl
Bross, David H.; Peterson, Kirk A.
2015-11-13
Spectroscopic constants (Te, re, B0, ωe, ωexe) have been calculated for the low-lying electronic states of UF, UF+, UCl, and UCl+ using complete active space 2nd-order perturbation theory (CASPT2), with a series of correlation consistent basis sets. The latter included those based on both pseudopotential (PP) and all-electron Douglas-Kroll-Hess (DK) Hamiltonians for the U atom. Spin orbit effects were included a posteri using the state interacting method using both PP and Breit Pauli (BP) operators, as well as from exact two-component (X2C) methods for U+ and UF+. Complete basis set (CBS) limits were obtained by extrapolation where possible and themore » PP and BP calculations were compared at their respective CBS limits. The PP-based method was shown to be reliable in calculating spectroscopic constants, in particular when using the state interacting method with CASPT2 energies (SO-CASPT2). The two component calculations were limited by computational resources and could not include electron correlation from the nominally closed shell 6s and 6p orbitals of U. UF and UCl were both calculated to have Ω=9/2 ground states. The first excited state of UCl was calculated to be an Ω=7/2 state at 78 cm-1 as opposed to the same state at 435 cm-1 in UF, and the other low-lying states of UCl showed a similar compression relative to UF. Likewise UF+ and UCl+ both have Ω=4 ground states and the manifold of low-lying excited Ω = 3, 2, 1, 0 states were energetically closer together in UCl+ than in UF+, ranging up to 776 cm-1 in UF+ and only 438 cm-1 in UCl+. As in previous research, the final PP-based SO-CASPT2 results for UF+ and UF agree well with experiment, and are expected to be predictive for UCl and UCl+, which are reported here for the first time.« less
Theoretical spectroscopy study of the low-lying electronic states of UX and UX{sup +}, X = F and Cl
Bross, David H.; Peterson, Kirk A.
2015-11-14
Spectroscopic constants (T{sub e}, r{sub e}, B{sub 0}, ω{sub e}, and ω{sub e}x{sub e}) have been calculated for the low-lying electronic states of UF, UF{sup +}, UCl, and UCl{sup +} using complete active space 2nd-order perturbation theory (CASPT2), with a series of correlation consistent basis sets. The latter included those based on both pseudopotential (PP) and all-electron Douglas-Kroll-Hess Hamiltonians for the U atom. Spin orbit (SO) effects were included a posteriori using the state interacting method using both PP and Breit Pauli (BP) operators, as well as from exact two-component methods for U{sup +} and UF{sup +}. Complete basis set (CBS) limits were obtained by extrapolation where possible and the PP and BP calculations were compared at their respective CBS limits. The PP-based method was shown to be reliable in calculating spectroscopic constants, in particular when using the state interacting method with CASPT2 energies (SO-CASPT2). The two component calculations were limited by computational resources and could not include electron correlation from the nominally closed shell 6s and 6p orbitals of U. UF and UCl were both calculated to have Ω = 9/2 ground states. The first excited state of UCl was calculated to be an Ω = 7/2 state at 78 cm{sup −1} as opposed to the same state at 435 cm{sup −1} in UF, and the other low-lying states of UCl showed a similar compression relative to UF. Likewise, UF{sup +} and UCl{sup +} both have Ω = 4 ground states and the manifold of low-lying excited Ω = 3, 2, 1, 0 states was energetically closer together in UCl{sup +} than in UF{sup +}, ranging up to 776 cm{sup −1} in UF{sup +} and only 438 cm{sup −1} in UCl{sup +}. As in previous studies, the final PP-based SO-CASPT2 results for UF{sup +} and UF agree well with experiment and are expected to be predictive for UCl and UCl{sup +}, which are reported here for the first time.
Electronic structure and rovibrational calculation of the low-lying states of the RbYb molecule
NASA Astrophysics Data System (ADS)
Tohme, S. N.; Korek, M.
2013-01-01
Complete Active Space Self Consistent Field (CASSCF) method with Multi Reference Configuration Interaction (MRCI) calculations is used to investigate the potential energy curves of the low-lying 29 electronic states in the representation 2s+1Λ(+/-) of the RbYb molecule (single and double excitations with Davidson corrections). The harmonic frequency ωe, the internuclear distance Re and the electronic energy with respect to the ground state Te have been calculated. The eigenvalues Ev, the rotational constant Bv, and the abscissas of the turning points Rmin and Rmax have been investigated using the canonical functions approach. The comparison between the values of the present work and those available in the literature for several states shows a very good agreement. Twenty-six new states have been studied here for the first time.
Structure of 10He low-lying states uncovered by correlations.
Sidorchuk, S I; Bezbakh, A A; Chudoba, V; Egorova, I A; Fomichev, A S; Golovkov, M S; Gorshkov, A V; Gorshkov, V A; Grigorenko, L V; Jalůvková, P; Kaminski, G; Krupko, S A; Kuzmin, E A; Nikolskii, E Yu; Oganessian, Yu Ts; Parfenova, Yu L; Sharov, P G; Slepnev, R S; Stepantsov, S V; Ter-Akopian, G M; Wolski, R; Yukhimchuk, A A; Filchagin, S V; Kirdyashkin, A A; Maksimkin, I P; Vikhlyantsev, O P
2012-05-18
The 0+ ground state of the 10He nucleus produced in the 3H(8He,p)10He reaction was found at about 2.1±0.2 MeV (Γ∼2 MeV) above the three-body ^{8}He+n+n breakup threshold. Angular correlations observed for ^{10}He decay products show prominent interference patterns allowing us to draw conclusions about the structure of low-energy excited states. We interpret the observed correlations as a coherent superposition of a broad 1- state having a maximum at energy 4-6 MeV and a 2+ state above 6 MeV, setting both on top of the 0+ state "tail." This anomalous level ordering indicates that the breakdown of the N=8 shell known in 12Be thus extends also to the ^{10}He system. PMID:23003144
Extensive theoretical studies on the low-lying electronic states of BBr+
NASA Astrophysics Data System (ADS)
Niu, Xianghong; Shu, Huabing; Zhu, Zunlue; Chen, Qian
2016-04-01
The potential energy curves (PECs) of two lowest dissociation channels of BBr+ have been thoroughly investigated using the internally contracted multireference configuration interaction method with Davidson correction and relativistic correction. All PECs are extrapolated to complete basis set limit. Several quasibound excited states caused by avoided crossings are found. Based on the PECs, the spectroscopic parameters of bound and quasibound states are obtained. The transition dipole moments and radiative lifetimes are predicted for all possible transitions. Finally, the spin-orbit coupling matrix elements are computed using the states interaction approach with the full Breit-Pauli Hamiltonian to analyze the interactions in PECs crossing regions. We propose that the 22Σ+-X2Σ+ and 22Π-X2Σ+ transitions which cannot be observed in experiments are attributed to the intricate couplings among 12Π, 22Π, 22Σ+, 14Σ+, 14Δ, 14Σ-, 12Δ and 12Σ- states.
The Low-Lying States of AlCu and AlAg
NASA Technical Reports Server (NTRS)
Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Partridge, Harry
1994-01-01
The singlet and triplet states of AlCu and AlAg below about 32 000/cm are studied using the internally contracted multireference configuration-interaction method. A more elaborate study of the X(sup 1)Sum(sup +) ground state of AlCu is undertaken using extended Gaussian basis sets, including the effect of inner-shell correlation and including a perturbational estimate of relativistic effects. Our best estimate of the spectroscopic constants (r(sub 0), DeltaG(sub 1/2), and D(sub 0)) for the X(sup 1)Sum(sup+) state with the experimental values in parentheses are: 4.416(4.420) a(sub 0), 295 (294) /cm, and 2.318 (2.315) eV. The calculations definitively assign the upper state in the observed transition at 14 892/cm to the lowest (sup 1)Prod state. The calculated spectroscopic constants and radiative lifetime for the (sup 1)Prod state are in good agreement with experiment. The calculations support the tentative assignments of Behm et al. for three band systems observed in the visible region between 25 000 and 28 000 / cm. However, the computed spectroscopic constants are in very poor agreement with those deduced from an analysis of the spectra. Analogous theoretical results for AlAg suggest that the (2)(sup 3)Prod, (3)(sup 3)Prod, and (3)(sup 1)Sum(sup +) states account for the bands observed, but not assigned, by Duncan and co-workers.
Structure of low-lying states in 140Sm studied by Coulomb excitation
NASA Astrophysics Data System (ADS)
Klintefjord, M.; Hadyńska-KlÈ©k, K.; Görgen, A.; Bauer, C.; Bello Garrote, F. L.; Bönig, S.; Bounthong, B.; Damyanova, A.; Delaroche, J.-P.; Fedosseev, V.; Fink, D. A.; Giacoppo, F.; Girod, M.; Hoff, P.; Imai, N.; Korten, W.; Larsen, A.-C.; Libert, J.; Lutter, R.; Marsh, B. A.; Molkanov, P. L.; Naïdja, H.; Napiorkowski, P.; Nowacki, F.; Pakarinen, J.; Rapisarda, E.; Reiter, P.; Renstrøm, T.; Rothe, S.; Seliverstov, M. D.; Siebeck, B.; Siem, S.; Srebrny, J.; Stora, T.; Thöle, P.; Tornyi, T. G.; Tveten, G. M.; Van Duppen, P.; Vermeulen, M. J.; Voulot, D.; Warr, N.; Wenander, F.; De Witte, H.; Zielińska, M.
2016-05-01
The electromagnetic structure of 140Sm was studied in a low-energy Coulomb excitation experiment with a radioactive ion beam from the REX-ISOLDE facility at CERN. The 2+ and 4+ states of the ground-state band and a second 2+ state were populated by multistep excitation. The analysis of the differential Coulomb excitation cross sections yielded reduced transition probabilities between all observed states and the spectroscopic quadrupole moment for the 21+ state. The experimental results are compared to large-scale shell model calculations and beyond-mean-field calculations based on the Gogny D1S interaction with a five-dimensional collective Hamiltonian formalism. Simpler geometric and algebraic models are also employed to interpret the experimental data. The results indicate that 140Sm shows considerable γ softness, but in contrast to earlier speculation no signs of shape coexistence at low excitation energy. This work sheds more light on the onset of deformation and collectivity in this mass region.
A study of the low-lying states of CaAr + and CaKr +
NASA Astrophysics Data System (ADS)
Heinemann, Christoph; Koch, Wolfram; Partridge, Harry
1998-04-01
The spectroscopic constants of the ground 2Σ + states of CaAr + and CaKr + are determined using high quality ab initio methods. The computed binding energies are 789 and 1252 cm -1, respectively, in good agreement with the experimental determination of Pullins, Scurlock, Reddic and Duncan (J. Chem. Phys. 104 (1996) 7518). The much smaller CaKr + binding energy determined by Buthelezi, Bellert, Lewis and Brucat (Chem. Phys. Lett. 246 (1995) 145) is shown to be due to deficiencies in the method used to approximate the binding energy of the excited state.
MRCI calculations of the low-lying electronic states of CuC
NASA Astrophysics Data System (ADS)
Liu, C.; Zhang, S. D.
2015-06-01
The four electronic states (2Σ-, 2Π, 4Σ-, and 4Π) of CuC corresponding to the lowest dissociation limits Cu(2 S g ) + C(3 P g ) are calculated by using multi-reference configuration interaction method with Davidson correction (MRCI + Q) approach in combination with the effective core potentials (ECPs) basis sets LANLTZ for the Cu atom and 6-311+g( d) basis sets for the C atom. The calculation covers the internuclear distance ranging from 0.04 to 0.54 nm, and the equilibrium bond length R e and the vertical excited energy T e are determined directly. The potential energy curves (PECs) show that the lowest two states are the 4Σ- and 2Π, and 4Σ- is the ground state where the 2Π state is higher than 4Σ- about 0.28 eV. With the potentials, all of the vibrational levels and rotational constants are predicted by numerically solving the radial Schröbinger equation of nuclear motion. Then the spectroscopic data of ωe, ωe x e, B e, and αe are obtained after data fitting which are compared with theoretical results currently available.
Theoretical study of the low-lying bound states of O2
NASA Technical Reports Server (NTRS)
Partridge, Harry; Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Taylor, Peter R.
1991-01-01
It is demonstrated that a complete-active-space self-consistent-field (CASSCF) (2p)/MRCI + Q (multireference configuration interaction with a Davidson correction) description in a (13s8p6d 4f2g)/((5s4p3d 2f1g) atomic natural orbits (ANO) basis set supplemented with diffuse functions provides a quantitative description of the six lowest states of O2. The calculated potentials are within 0.05 eV (1.2 kilocal/mol) of accurate experimental results. The importance of substantially expanding the primitive basis set has been investigated, and it is demonstrated that such expansions yield insignificant improvement in the spectroscopic constants. Potential energy curves have also been reported for the weakly bound states of O2. The 5Pi(g) state is estimated to have a D(e) of 0.16 +/- 0.03 eV. The upper bound of D(e) is found to be sufficiently large that the importance of this state as a precursor for the formation of O2 (b 1Sigma(t)(+)) and O(1S) should be reconsidered.
Probing ground and low-lying excited states for HIO2 isomers
NASA Astrophysics Data System (ADS)
de Souza, Gabriel L. C.; Brown, Alex
2014-12-01
We present a computational study on HIO2 molecules. Ground state properties such as equilibrium structures, relative energetics, vibrational frequencies, and infrared intensities were obtained for all the isomers at the coupled-cluster with single and double excitations as well as perturbative inclusion of triples (CCSD(T)) level of theory with the aug-cc-pVTZ-PP basis set and ECP-28-PP effective core potential for iodine and the aug-cc-pVTZ basis set for hydrogen and oxygen atoms. The HOIO structure is confirmed as the lowest energy isomer. The relative energies are shown to be HOIO < HOOI < HI(O)O. The HO(O)I isomer is only stable at the density functional theory (DFT) level of theory. The transition states determined show interconversion of the isomers is possible. In order to facilitate future experimental identification, vibrational frequencies are also determined for all corresponding deuterated species. Vertical excitation energies for the three lowest-lying singlet and triplet excited states were determined using the configuration interaction singles, time-dependent density functional theory (TD-DFT)/B3LYP, TD-DFT/G96PW91, and equation of motion-CCSD approaches with the LANL2DZ basis set plus effective core potential for iodine and the aug-cc-pVTZ basis set for hydrogen and oxygen atoms. It is shown that HOIO and HOOI isomers have excited states accessible at solar wavelengths (<4.0 eV) but these states have very small oscillator strengths (<2 × 10-3).
Probing ground and low-lying excited states for HIO2 isomers.
de Souza, Gabriel L C; Brown, Alex
2014-12-21
We present a computational study on HIO2 molecules. Ground state properties such as equilibrium structures, relative energetics, vibrational frequencies, and infrared intensities were obtained for all the isomers at the coupled-cluster with single and double excitations as well as perturbative inclusion of triples (CCSD(T)) level of theory with the aug-cc-pVTZ-PP basis set and ECP-28-PP effective core potential for iodine and the aug-cc-pVTZ basis set for hydrogen and oxygen atoms. The HOIO structure is confirmed as the lowest energy isomer. The relative energies are shown to be HOIO < HOOI < HI(O)O. The HO(O)I isomer is only stable at the density functional theory (DFT) level of theory. The transition states determined show interconversion of the isomers is possible. In order to facilitate future experimental identification, vibrational frequencies are also determined for all corresponding deuterated species. Vertical excitation energies for the three lowest-lying singlet and triplet excited states were determined using the configuration interaction singles, time-dependent density functional theory (TD-DFT)/B3LYP, TD-DFT/G96PW91, and equation of motion-CCSD approaches with the LANL2DZ basis set plus effective core potential for iodine and the aug-cc-pVTZ basis set for hydrogen and oxygen atoms. It is shown that HOIO and HOOI isomers have excited states accessible at solar wavelengths (<4.0 eV) but these states have very small oscillator strengths (<2 × 10(-3)). PMID:25527931
Probing ground and low-lying excited states for HIO{sub 2} isomers
Souza, Gabriel L. C. de; Brown, Alex
2014-12-21
We present a computational study on HIO{sub 2} molecules. Ground state properties such as equilibrium structures, relative energetics, vibrational frequencies, and infrared intensities were obtained for all the isomers at the coupled-cluster with single and double excitations as well as perturbative inclusion of triples (CCSD(T)) level of theory with the aug-cc-pVTZ-PP basis set and ECP-28-PP effective core potential for iodine and the aug-cc-pVTZ basis set for hydrogen and oxygen atoms. The HOIO structure is confirmed as the lowest energy isomer. The relative energies are shown to be HOIO < HOOI < HI(O)O. The HO(O)I isomer is only stable at the density functional theory (DFT) level of theory. The transition states determined show interconversion of the isomers is possible. In order to facilitate future experimental identification, vibrational frequencies are also determined for all corresponding deuterated species. Vertical excitation energies for the three lowest-lying singlet and triplet excited states were determined using the configuration interaction singles, time-dependent density functional theory (TD-DFT)/B3LYP, TD-DFT/G96PW91, and equation of motion-CCSD approaches with the LANL2DZ basis set plus effective core potential for iodine and the aug-cc-pVTZ basis set for hydrogen and oxygen atoms. It is shown that HOIO and HOOI isomers have excited states accessible at solar wavelengths (<4.0 eV) but these states have very small oscillator strengths (<2 × 10{sup −3})
Low-lying excited states in the neutron-deficient isotopes 163Os and 165Os
NASA Astrophysics Data System (ADS)
Drummond, M. C.; Joss, D. T.; Page, R. D.; Simpson, J.; O'Donnell, D.; Andgren, K.; Bianco, L.; Cederwall, B.; Darby, I. G.; Eeckhaudt, S.; Gomez-Hornillos, M. B.; Grahn, T.; Greenlees, P. T.; Hadinia, B.; Jones, P. M.; Julin, R.; Juutinen, S.; Ketelhut, S.; Leppänen, A.-P.; Leino, M.; Nyman, M.; Pakarinen, J.; Rahkila, P.; Sandzelius, M.; Sapple, P. J.; Sarén, J.; Saygi, B.; Scholey, C.; Sorri, J.; Thomson, J.; Uusitalo, J.; Venhart, M.
2013-05-01
Excited states in the neutron-deficient isotopes 163Os and 165Os were identified using the JUROGAM and GREAT spectrometers in conjunction with the RITU gas-filled separator. The 163Os and 165Os nuclei were populated via the 106Cd(60Ni,3n) and 92Mo(78Kr,2p3n) reactions at bombarding energies of 270 MeV and 357 MeV, respectively. Gamma-ray emissions from these nuclei have been established unambiguously using the recoil-decay tagging technique and a coincidence analysis has allowed level schemes to be established. These results suggest that the yrast states are based upon negative-parity configurations originating from the νf7/2 and νh9/2 orbitals.
Spectroscopic and theoretical studies of the low-lying states of BaO{sup +}
Bartlett, Joshua H.; VanGundy, Robert A.; Heaven, Michael C.
2015-07-28
The BaO{sup +} cation is of interest from the perspectives of electronic structure and the potential for cooling to ultra-cold temperatures. Spectroscopic data for the ion have been obtained using a two-color photoionization technique. The ionization energy for BaO was found to be 6.8123(3) eV. The ground state of BaO{sup +} was identified as X{sup 2}Σ{sup +}, and both vibrational and rotational constants were determined. Vibrationally resolved spectra were recorded for A{sup 2}Π, the first electronically excited state. These data yielded the term energy, vibrational frequency, and the spin-orbit interaction constant. Relativistic electronic structure calculations were carried out using multi-reference configuration interaction (MRCI), coupled cluster and density functional theory methods. Transition moments for the pure vibrational and A{sup 2}Π-X{sup 2}Σ{sup +} transitions were predicted using the MRCI method.
Electron-impact excitation of the low-lying electronic states of formaldehyde
NASA Technical Reports Server (NTRS)
Chutjian, A.
1974-01-01
Electron-impact excitation has been observed at incident electron energies of 10.1 and 20.1 eV to the first five excited electronic states of formaldehyde lying at and below the 1B2 state at 7.10 eV. These excitations include two new transitions in the energy-loss range 5.6-6.2 eV and 6.7-7.0 eV which have been detected for the first time, either through electron-impact excitation or photon absorption. The differential cross sections of these new excitations are given at scattering angles between 15 and 135 deg. These cross-section ratios peak at large scattering angles - a characteristic of triplet - singlet excitations. The design and performance of the electron-impact spectrometer used in the above observations is outlined and discussed.
Mechanisms of deactivation of the low-lying electronic states of 2,2 prime -bipyridine
Castellucci, E.; Angeloni, L. ); Marconi, G.; Venuti, E. ); Baraldi, I. )
1990-03-08
The photophysical properties of 2,2{prime}-bipyridine have been investigated in different solvents by means of lifetime measurements on the picosecond scale, quantum yield temperature dependence, and CS-INDO CI calculations. Both experimental and theoretical results indicate that in inert solvents the very low fluorescence quantum yield of this molecule is due to a very effective intersystem crossing to a local triplet state. The picture emerging from these data helps to gain insight into the elusive photophysical behavior of this compound.
Electron impact excitation and assignment of the low-lying electronic states of CO2
NASA Technical Reports Server (NTRS)
Hall, R. I.; Trajmar, S.
1973-01-01
Electron scattering spectra of CO2 are reported in the 7 to 10 eV energy-loss range, at energies of 0.2, 0.35, 0.6, 0.7, and 7.0 eV above threshold, and at a scattering angle of 90 deg. Several new distinct overlapping continua with weak, diffuse bands superimposed are observed to lie in this energy-loss range. The experimental spectra are discussed in the light of recent ab initio configuration-interaction calculations of the vertical transition energies of CO2. The experimental spectra are shown to be consistent with the excitation states of CO2.
NASA Astrophysics Data System (ADS)
Lei, Y.
2016-02-01
In random-interaction ensembles, three proportional correlations between quadrupole moments of the first two Iπ=2+ states robustly emerge, including Q (21+) =±Q (22+) correlations previously remarked by a realistic nuclear survey, and the Q (22+) =-3/7 Q (21+) correlation, which is only observed in the s d -boson space. These correlations can be microscopically characterized by the rotational SU(3) symmetry and quadrupole vibrational U(5) limit, respectively, according to the Elliott model and the s d -boson mean-field theory. The anharmonic vibration may be another phenomenological interpretation for the Q (21+) =-Q (22+) correlation, whose spectral evidence, however, is insufficient.
Reduced transition strengths of low-lying yrast states in chromium isotopes in the vicinity of N =40
NASA Astrophysics Data System (ADS)
Braunroth, Thomas; Dewald, A.; Iwasaki, H.; Lenzi, S. M.; Albers, M.; Bader, V. M.; Baugher, T.; Baumann, T.; Bazin, D.; Berryman, J. S.; Fransen, C.; Gade, A.; Ginter, T.; Gottardo, A.; Hackstein, M.; Jolie, J.; Lemasson, A.; Litzinger, J.; Lunardi, S.; Marchi, T.; Modamio, V.; Morse, C.; Napoli, D. R.; Nichols, A.; Recchia, F.; Stroberg, S. R.; Wadsworth, R.; Weisshaar, D.; Whitmore, K.; Wimmer, K.
2015-09-01
Background: In neutron-rich nuclei around N =40 rapid changes in nuclear structure can be observed. While 68Ni exhibits signatures of a doubly magic nucleus, experimental data along the isotopic chains in even more exotic Fe and Cr isotopes—such as excitation energies and transition strengths—suggest a sudden rise in collectivity toward N =40 . Purpose: Reduced quadrupole transition strengths for low-lying transitions in neutron-rich 58,60,62Cr are investigated. This gives quantitative new insights into the evolution of quadrupole collectivity in the neutron-rich region close to N =40 . Method: The recoil distance Doppler-shift (RDDS) technique was applied to measure lifetimes of low-lying states in 58,60,62>Cr. The experiment was carried out at the National Superconducting Cyclotron Laboratory (NSCL) with the SeGA array in a plunger configuration coupled to the S800 magnetic spectrograph. The states of interest were populated by means of one-proton knockout reactions. Results: Data reveal a rapid increase in quadrupole collectivity for 58,60,62>Cr toward N =40 and point to stronger quadrupole deformations compared to neighboring Fe isotopes. The experimental B (E 2 ) values are reproduced well with state-of-the-art shell-model calculations using the LNPS effective interaction. A consideration of intrinsic quadrupole moments and B42 ratios suggest an evolution toward a rotational nature of the collective structures in Cr,6260. Compared to 58Cr, experimental B42 and B62 values for 60Cr are in better agreement with the E (5 ) limit. Conclusion: Our results indicate that collective excitations in neutron-rich Cr isotopes saturate at N =38 , which is in agreement with theoretical predictions. More detailed experimental data of excited structures and interband transitions are needed for a comprehensive understanding of quadrupole collectivity close to N =40 . This calls for additional measurements in neutron-rich Cr and neighboring Ti and Fe nuclei.
Relativistic MR-MP energy levels: Low-lying states in the Mg isoelectronic sequence
NASA Astrophysics Data System (ADS)
Santana, Juan A.
2016-09-01
The relativistic Multi-Reference Møller-Plesset (MR-MP) many-body perturbation theory was applied to calculate the energies of all excited states within the 3s3p, 3p2, 3s3d, 3p3d and 3d2 configurations for every ion of the Mg isoelectronic sequence (Z = 12 - 100). The results are compared with previous calculations and available experimental data. The MR-MP excitation energies agree with experiment typically within 100 ppm over a wide range of Z, particularly for mid- and high-range Z. Experimental data for highly charged ions in this isoelectronic sequence are limited and the complete and accurate dataset presented here is expected to ease the identification process upon measurements.
Low-lying excited states and nonradiative processes of 9-methyl-2-aminopurine
Trachsel, Maria A.; Lobsiger, Simon; Schär, Tobias; Leutwyler, Samuel
2014-01-28
The UV spectrum of the adenine analogue 9-methyl-2-aminopurine (9M-2AP) is investigated with one- and two-color resonant two-photon ionization spectroscopy at 0.3 and 0.05 cm{sup −1} resolution in a supersonic jet. The electronic origin at 32 252 cm{sup −1} exhibits methyl torsional subbands that originate from the 0A{sub 1}{sup ′′} (l = 0) and 1E{sup ″} (l = ±1) torsional levels. These and further torsional bands that appear up to 0{sub 0}{sup 0}+230 cm{sup −1} allow to fit the threefold (V{sub 3}) barriers of the torsional potentials as |V{sub 3}{sup ′′}|=50 cm{sup −1} in the S{sub 0} and |V{sub 3}{sup ′}|=126 cm{sup −1} in the S{sub 1} state. Using the B3LYP density functional and correlated approximate second-order coupled cluster CC2 methods, the methyl orientation is calculated to be symmetric relative to the 2AP plane in both states, with barriers of V{sub 3}{sup ′′}=20 cm{sup −1} and V{sub 3}{sup ′}=115 cm{sup −1}. The 0{sub 0}{sup 0} rotational band contour is 75% in-plane (a/b) polarized, characteristic for a dominantly long-axis {sup 1}ππ{sup *} excitation. The residual 25% c-axis polarization may indicate coupling of the {sup 1}ππ{sup *} to the close-lying {sup 1}nπ{sup *} state, calculated at 4.00 and 4.01 eV with the CC2 method. However, the CC2 calculated {sup 1}nπ oscillator strength is only 6% of that of the {sup 1}ππ{sup *} transition. The {sup 1}ππ{sup *} vibronic spectrum is very complex, showing about 40 bands within the lowest 500 cm{sup −1}. The methyl torsion and the low-frequency out-of-plane ν{sub 1}{sup ′} and ν{sub 2}{sup ′} vibrations are strongly coupled in the {sup 1}ππ{sup *} state. This gives rise to many torsion-vibration combination bands built on out-of-plane fundamentals, which are without precedence in the {sup 1}ππ{sup *} spectrum of 9H-2-aminopurine [S. Lobsiger, R. K. Sinha, M. Trachsel, and S. Leutwyler, J. Chem. Phys. 134, 114307 (2011)]. From the Lorentzian
State of Louisiana - Highlighting Low-Lying Areas Derived from USGS Digital Elevation Data
Kosovich, John J.
2008-01-01
In support of U.S. Geological Survey (USGS) disaster preparedness efforts, this map depicts a color shaded relief representation highlighting the State of Louisiana and depicts the surrounding areas using muted elevation colors. The first 30 feet of relief above mean sea level are displayed as brightly colored 5-foot elevation bands, which highlight low-elevation areas at a coarse spatial resolution. Areas below sea level typically are surrounded by levees or some other type of flood-control structures. Standard USGS National Elevation Dataset (NED) 1 arc-second (nominally 30-meter) digital elevation model (DEM) data are the basis for the map, which is designed to be used at a broad scale and for informational purposes only. The NED data are a mixture of data and were derived from the original 1:24,000-scale USGS topographic map bare-earth contours, which were converted into gridded quadrangle-based DEM tiles at a constant post spacing (grid cell size) of either 30 meters (data before the mid-1990s) or 10 meters (mid-1990s and later data). These individual-quadrangle DEMs were then converted to spherical coordinates (latitude/longitude decimal degrees) and edge-matched to ensure seamlessness. Approximately one-half of the area shown on this map has DEM source data at a 30-meter resolution, with the remaining half consisting of mostly 10-meter contour-derived DEM data and some small areas of higher-resolution LIght Detection And Ranging (LIDAR) data along parts of the coastline. Areas below sea level typically are surrounded by levees or some other type of flood-control structures. State and parish boundary, hydrography, city, and road layers were modified from USGS National Atlas data downloaded in 2003. The NED data were downloaded in 2007.
Karmakar, Shreetama; Mukhopadhyay, Deb Pratim; Chakraborty, Tapas
2015-05-14
Multiple fluorine atom substitution effect on photophysics of an aromatic chromophore has been investigated using phenol as the reference system. It has been noticed that the discrete vibronic structure of the S{sub 1}←S{sub 0} absorption system of phenol vapor is completely washed out for pentafluorophenol (PFP), and the latter also shows very large Stokes shift in the fluorescence spectrum. For excitations beyond S{sub 1} origin, the emission yield of PFP is reduced sharply with increase in excess vibronic energy. However, in a collisional environment like liquid hydrocarbon, the underlying dynamical process that drives the non-radiative decay is hindered drastically. Electronic structure theory predicts a number of low-lying dark electronic states of πσ{sup ∗} character in the vicinity of the lowest valence ππ{sup ∗} state of this molecule. Tentatively, we have attributed the excitation energy dependent non-radiative decay of the molecule observed only in the gas phase to an interplay between the lowest ππ{sup ∗} and a nearby dissociative πσ{sup ∗} state. Measurements in different liquids reveal that some of the dark excited states light up with appreciable intensity only in protic liquids like methanol and water due to hydrogen bonding between solute and solvents. Electronic structure theory methods indeed predict that for PFP-(H{sub 2}O){sub n} clusters (n = 1-11), intensities of a number of πσ{sup ∗} states are enhanced with increase in cluster size. In contrast with emitting behavior of the molecule in the gas phase and solutions of nonpolar and polar aprotic liquids, the fluorescence is completely switched off in polar protic liquids. This behavior is a chemically significant manifestation of perfluoro effect, because a very opposite effect occurs in the case of unsubstituted phenol for which fluorescence yield undergoes a very large enhancement in protic liquids. Several dynamical mechanisms have been suggested to interpret the
Lee, Jae-Kwang; Fujiwara, Takashige; Kofron, William G.; Zgierski, Marek Z.; Lim, Edward C.
2008-04-28
Electronic absorption spectra of the low-lying {pi}{pi}* and {pi}{sigma}* states of several aminobenzonitriles and 4-dimethylaminobenzethyne have been studied by time-resolved transient absorption and time-dependent density functional theory calculation. In acetonitrile, the lifetime of the {pi}{sigma}*-state absorption is very short (picoseconds or subpicosecond) for molecules that exhibit intramolecular charge transfer (ICT), and very long (nanoseconds) for those that do not. Where direct comparison of the temporal characteristics of the {pi}{sigma}*-state and the ICT-state transients could be made, the formation rate of the ICT state is identical to the decay rate of the {pi}{sigma}* state within the experimental uncertainty. These results are consistent with the {pi}{sigma}*-mediated ICT mechanism, L{sub a} ({pi}{pi}*){yields}{pi}{sigma}*{yields}ICT, in which the decay rate of the {pi}{sigma}* state is determined by the rate of the solvent-controlled {pi}{sigma}*{yields}ICT charge-shift reaction. The {pi}{pi}*{yields}{pi}{sigma}* state crossing does not occur in 3-dimethylaminobenzonitrile or 2-dimethylaminobenzonitrile, as predicted by the calculation, and 4-aminobenzonitrile and 4-dimethylaminobenzethyne does not exhibit the ICT reaction, consistent with the higher energy of the ICT state relative to the {pi}{sigma}* state.
State of Texas - Highlighting Low-Lying Areas Derived from USGS Digital Elevation Data
Kosovich, John J.
2008-01-01
In support of U.S. Geological Survey (USGS) disaster preparedness efforts, this map depicts a color shaded relief representation of Texas and a grayscale relief of the surrounding areas. The first 30 feet of relief above mean sea level are displayed as brightly colored 5-foot elevation bands, which highlight low-elevation areas at a coarse spatial resolution. Standard USGS National Elevation Dataset (NED) 1 arc-second (nominally 30-meter) digital elevation model (DEM) data are the basis for the map, which is designed to be used at a broad scale and for informational purposes only. The NED data were derived from the original 1:24,000-scale USGS topographic map bare-earth contours, which were converted into gridded quadrangle-based DEM tiles at a constant post spacing (grid cell size) of either 30 meters (data before the mid-1990s) or 10 meters (mid-1990s and later data). These individual-quadrangle DEMs were then converted to spherical coordinates (latitude/longitude decimal degrees) and edge-matched to ensure seamlessness. The NED source data for this map consists of a mixture of 30-meter- and 10-meter-resolution DEMs. State and county boundary, hydrography, city, and road layers were modified from USGS National Atlas data downloaded in 2003. The NED data were downloaded in 2002. Shaded relief over Mexico was obtained from the USGS National Atlas.
Li, Shaohong L; Xu, Xuefei; Truhlar, Donald G
2015-08-21
Three singlet states, namely a closed-shell ground state and two excited states with (1)ππ* and (1)nσ* character, have been suggested to be responsible for the radiationless decay or photochemical reaction of photoexcited thioanisole. The correct interpretation of the electronic spectrum is critical for understanding the character of these low-lying excited states, but the experimental spectrum is yet to be fully interpreted. In the work reported here, we investigated the nature of those three states and a fourth singlet state of thioanisole using electronic structure calculations by multireference perturbation theory, by completely-renormalized equation-of-motion coupled cluster theory with single and double excitations and noniterative inclusion of connected triples (CR-EOM-CCSD(T)), and by linear-response time-dependent density functional theory (TDDFT). We clarified the assignment of the electronic spectrum by simulating it using a normal-mode sampling approach combined with TDDFT in the Tamm-Dancoff approximation (TDA). The understanding of the electronic states and of the accuracy of the electronic structure methods lays the foundation of our future work of constructing potential energy surfaces. PMID:26088195
Tohme, Samir N.; Korek, Mahmoud E-mail: fkorek@yahoo.com; Awad, Ramadan
2015-03-21
Ab initio techniques have been applied to investigate the electronic structure of the LiYb molecule. The potential energy curves have been computed in the Born–Oppenheimer approximation for the ground and 29 low-lying doublet and quartet excited electronic states. Complete active space self-consistent field, multi-reference configuration interaction, and Rayleigh Schrödinger perturbation theory to second order calculations have been utilized to investigate these states. The spectroscopic constants, ω{sub e}, R{sub e}, B{sub e}, …, and the static dipole moment, μ, have been investigated by using the two different techniques of calculation with five different types of basis. The eigenvalues, E{sub v}, the rotational constant, B{sub v}, the centrifugal distortion constant, D{sub v}, and the abscissas of the turning points, R{sub min} and R{sub max}, have been calculated by using the canonical functions approach. The comparison between the values of the present work, calculated by different techniques, and those available in the literature for several electronic states shows a very good agreement. Twenty-one new electronic states have been studied here for the first time.
Tohme, Samir N; Korek, Mahmoud; Awad, Ramadan
2015-03-21
Ab initio techniques have been applied to investigate the electronic structure of the LiYb molecule. The potential energy curves have been computed in the Born-Oppenheimer approximation for the ground and 29 low-lying doublet and quartet excited electronic states. Complete active space self-consistent field, multi-reference configuration interaction, and Rayleigh Schrödinger perturbation theory to second order calculations have been utilized to investigate these states. The spectroscopic constants, ωe, Re, Be, …, and the static dipole moment, μ, have been investigated by using the two different techniques of calculation with five different types of basis. The eigenvalues, Ev, the rotational constant, Bv, the centrifugal distortion constant, Dv, and the abscissas of the turning points, Rmin and Rmax, have been calculated by using the canonical functions approach. The comparison between the values of the present work, calculated by different techniques, and those available in the literature for several electronic states shows a very good agreement. Twenty-one new electronic states have been studied here for the first time. PMID:25796254
NASA Astrophysics Data System (ADS)
Tohme, Samir N.; Korek, Mahmoud; Awad, Ramadan
2015-03-01
Ab initio techniques have been applied to investigate the electronic structure of the LiYb molecule. The potential energy curves have been computed in the Born-Oppenheimer approximation for the ground and 29 low-lying doublet and quartet excited electronic states. Complete active space self-consistent field, multi-reference configuration interaction, and Rayleigh Schrödinger perturbation theory to second order calculations have been utilized to investigate these states. The spectroscopic constants, ωe, Re, Be, …, and the static dipole moment, μ, have been investigated by using the two different techniques of calculation with five different types of basis. The eigenvalues, Ev, the rotational constant, Bv, the centrifugal distortion constant, Dv, and the abscissas of the turning points, Rmin and Rmax, have been calculated by using the canonical functions approach. The comparison between the values of the present work, calculated by different techniques, and those available in the literature for several electronic states shows a very good agreement. Twenty-one new electronic states have been studied here for the first time.
Study of low-lying electronic states of ozone by multireference Møller-Plesset perturbation method
NASA Astrophysics Data System (ADS)
Tsuneda, T.; Nakano, H.; Hirao, K.
1995-10-01
The geometry and relative energy of the seven low-lying electronic states of ozone and the ground state of ozonide anion have been determined in C2v symmetry by the complete active space self-consistent field (CASSCF) and the multireference Møller-Plesset perturbation (MRMP) methods. The results are compared with the photodetachment spectra of O-3 observed recently by Arnold et al. The theoretical electron affinity of ozone is 1.965 eV, which is 0.14 eV below the experimental result of 2.103 eV. The calculated adiabatic excitation energies (assignment of Arnold et al. in parentheses) of ozone are 3A2 0.90 eV (1.18 eV), 3B2, 1.19 eV (1.30 eV), 3B1, 1.18 eV (1.45 eV), 1A2, 1.15 eV (˜1.6 eV), 1B1, 1.65 eV (2.05 eV), and 1B2, 3.77 eV (3.41 eV), respectively. Overall the present theory supports the assignment of Arnold et al. However, the simple considerations of geometry and energy are insufficient to determine a specific assignment of the 3B2 and 3B1 states. The dissociation energy of the ground state of ozone is computed to be 0.834 eV at the present level of theory. The present theory also predicts that none of the excited states lies below the ground state dissociation limit of O3.
Ab initio MRSDCI study on the low-lying electronic states of the lithium chloride molecule (LiCl)
NASA Astrophysics Data System (ADS)
Kurosaki, Yuzuru; Yokoyama, Keiichi
2012-08-01
Potential energy curves (PECs) for the low-lying states of the lithium chloride molecule (LiCl) have been calculated using the internally contracted multireference single- and double-excitation configuration interaction (MRSDCI) method with the aug-cc-PVnZ (AVnZ) and aug-cc-PCVnZ (ACVnZ) basis sets, where n = T, Q, and 5. First, we calculate PECs for 7 spin-orbit (SO)-free Λ-S states, X1Σ+, A1Σ+, 3Σ+, 1Π, and 3Π, and then obtain PECs for 13 SO Ω states, X0+, A0+, B0+, 0-(I), 0-(II), 1(I), 1(II), 1(III), and 2, by diagonalizing the matrix of the electronic Hamiltonian plus the Breit-Pauli SO Hamiltonian. The MRSDCI calculations not including core orbital correlation through the single and double excitations are also performed with the AV5Z and ACV5Z basis sets. The Davidson corrections (Q0) are added to both the Λ-S and Ω state energies. Vibrational eigenstates for the obtained X1Σ+ and X0+ PECs are calculated by solving the time-independent Schrödinger equation with the grid method. Thus, the effects of basis set, core orbital correlation, and the Davidson correction on the X1Σ+ and X0+ PECs of LiCl are investigated by comparing the spectroscopic constants calculated from the PECs with one another and with experiment. It is confirmed that to accurately predict the spectroscopic constants we need to include core-electron correlation in the CI expansion and use the basis sets designed to describe core-valence correlation, i.e., ACVnZ. The SO PECs presented in this paper will be of help in the future study of diatomic alkali halide dynamics.
Ab initio MRSDCI study on the low-lying electronic states of the lithium chloride molecule (LiCl).
Kurosaki, Yuzuru; Yokoyama, Keiichi
2012-08-14
Potential energy curves (PECs) for the low-lying states of the lithium chloride molecule (LiCl) have been calculated using the internally contracted multireference single- and double-excitation configuration interaction (MRSDCI) method with the aug-cc-PVnZ (AVnZ) and aug-cc-PCVnZ (ACVnZ) basis sets, where n = T, Q, and 5. First, we calculate PECs for 7 spin-orbit (SO)-free Λ-S states, X(1)Σ(+), A(1)Σ(+), (3)Σ(+), (1)Π, and (3)Π, and then obtain PECs for 13 SO Ω states, X0(+), A0(+), B0(+), 0(-)(I), 0(-)(II), 1(I), 1(II), 1(III), and 2, by diagonalizing the matrix of the electronic Hamiltonian plus the Breit-Pauli SO Hamiltonian. The MRSDCI calculations not including core orbital correlation through the single and double excitations are also performed with the AV5Z and ACV5Z basis sets. The Davidson corrections (Q0) are added to both the Λ-S and Ω state energies. Vibrational eigenstates for the obtained X(1)Σ(+) and X0(+) PECs are calculated by solving the time-independent Schrödinger equation with the grid method. Thus, the effects of basis set, core orbital correlation, and the Davidson correction on the X(1)Σ(+) and X0(+) PECs of LiCl are investigated by comparing the spectroscopic constants calculated from the PECs with one another and with experiment. It is confirmed that to accurately predict the spectroscopic constants we need to include core-electron correlation in the CI expansion and use the basis sets designed to describe core-valence correlation, i.e., ACVnZ. The SO PECs presented in this paper will be of help in the future study of diatomic alkali halide dynamics. PMID:22897271
NASA Technical Reports Server (NTRS)
Bauschlicher, C. W., Jr.; Silver, D. M.; Yarkony, D. R.
1980-01-01
The paper presents the multiconfiguration-self-consistent (MCSCF) and configuration state functions (CSF) for the low-lying electronic states of MgO. It was shown that simple description of these states was possible provided the 1 Sigma(+) states are individually optimized at the MCSCF level, noting that the 1(3 Sigma)(+) and 2(1 Sigma)(+) states which nominally result from the same electron occupation are separated energetically. The molecular orbitals obtained at this level of approximation should provide a useful starting point for extended configuration interaction calculations since they have been optimized for the particular states of interest.
NASA Astrophysics Data System (ADS)
Samala, Nagaprasad Reddy; Mahapatra, S.
2014-06-01
Polycyclic aromatic hydrocarbons (PAHs), in particular, their radical cation (PAH^+), have long been postulated to be the important molecular species in connection with the spectroscopic observations in the interstellar medium. Motivated by numerous important observations by stellar as well as laboratory spectroscopists, we undertook detailed quantum mechanical studies of the structure and dynamics of electronically excited PAH^+ in an attempt to establish possible synergism with the recorded data In this study, we focus on the quantum chemistry and dynamics of the doublet ground (X) and low-lying excited (A, B and C) electronic states of the radical cation of tetracene (Tn), pentacene (Pn), and hexacene (Hn) molecule. This study is aimed to unravel photostability, spectroscopy, and time-dependent dynamics of their excited electronic states. In order to proceed with the theoretical investigations, we construct suitable multistate and multimode Hamiltonian for these systems with the aid of extensive ab initio calculations of their electronic energy surfaces. The diabatic coupling surfaces are derived from the calculated adiabatic electronic energies. First principles nuclear dynamics calculations are then carried out employing the constructed Hamiltonians and with the aid of time-independent and time-dependent quantum mechanical methods. We compared our theoretical results with available photoelectron spectroscopy, zero kinetic energy photoelectron (ZEKE) spectroscopy and matrix isolation spectroscopy (MIS) results. A peak at 8650 Å in the B state spectrum of Tn^+ is in good agreement with the DIB at 8648 Å observed by Salama et al. Similarly in Pn^+, a peak at 8350 Å can be correlated to the DIB at 8321 Å observed by Salama et al. J. Zhang et al., J. Chem. Phys., 128,104301 (2008).; F. Salama, Origins of Life Evol. Biosphere, 28, 349 (1998).; F. Salama et al., Planet. Space Sci., 43, 1165 (1995).; F. Salama et al., Astrophys. J., 526, 265 (1999).; J
NASA Astrophysics Data System (ADS)
Berriche, Hamid; Gadea, Florent Xavier
1995-12-01
The permanent dipole moments of the eight low-lying 1Σ states of the LiH molecule are calculated by an ab initio approach for both the adiabatic and the diabatic representations. The results shed light on the interplay between the ionic and the neutral states producing a direct illustration of the ionic character of the electronic wavefunction. Our results suggest that the location and the width of the avoided crossings for the potential energy curves could be experimentally derived.
Narra, Sudhakar; Shigeto, Shinsuke
2015-03-01
Low-lying excited triplet states of aromatic carbonyl compounds exhibit diverse photophysical and photochemical properties of fundamental importance. Despite tremendous effort in studying those triplet states, the effects of substituents and solvents on the energetics of the triplet manifold and on photoreactivity remain to be fully understood. We have recently studied the ordering of the low-lying nπ* and ππ* excited triplet states and its substituent dependence in acetophenone derivatives using nanosecond time-resolved near-IR (NIR) spectroscopy. Here we address the other important issue, the solvent effects, by directly observing the electronic bands in the NIR that originate from the lowest nπ* and ππ* states of acetophenone derivatives in four solvents of different polarity (n-heptane, benzene, acetonitrile, and methanol). The two transient NIR bands decay synchronously in all the solvents, indicating that the lowest nπ* and ππ* states are in thermal equilibrium irrespective of the solvent polarity studied here. We found that the ππ* band increases in intensity relative to the nπ* band as solvent polarity increases. These results are compared with the photoreduction rate constant for the acetophenone derivatives in the solvents to which 2-propanol was added as a hydrogen-atom donor. Based on the present findings, we present a comprehensive, solvent- and substituent-dependent energy level diagram of the low-lying nπ* and ππ* excited triplet states. PMID:25686256
A potential-energy surface study of the 2A1 and low-lying dissociative states of the methoxy radical
NASA Technical Reports Server (NTRS)
Jackels, C. F.
1985-01-01
Accurate, ab initio quantum chemical techniques are applied in the present study of low lying bound and dissociative states of the methoxy radical at C3nu conformations, using a double zeta quality basis set that is augmented with polarization and diffuse functions. Excitation energy estimates are obtained for vertical excitation, vertical deexcitation, and system origin. The rate of methoxy photolysis is estimated to be too small to warrant its inclusion in atmospheric models.
Bergeman, T.; Fellows, C.E.; Gutterres, R.F.; Amiot, C.
2003-05-01
Analysis and assignment of spectra involving the lowest excited states of the heavier alkali-metal atom dimers are complicated by the strong spin-orbit coupling elements. Here we report an analysis of the Fourier-transform spectroscopy data from laser-induced fluorescence of the coupled A {sup 1}{sigma}{sup +} and b {sup 3}{pi} states of RbCs, using the discrete variable representation. Fitted parameters are given and special effects due to strong coupling are discussed.
Zou, Wenli; Suo, Bingbing
2016-08-18
The low-lying electronic states of platinum ions (Pt(+)) and platinum monohalides (PtX; X = F, Cl, Br, and I) are calculated using the multireference configuration interaction method with relativistic effective core potentials. The spin-orbit coupling is taken into account through the perturbative state-interaction approach. For the Ω states of PtX below 35000 cm(-1), the potential energy curves and the corresponding spectroscopic constants are reported. It is found that the lowest Ω = 3/2 state is the ground one for the four species of PtX. Overall, the theoretical results are in reasonable agreement with the available experimental data. PMID:27463417
Kowalski, Karol; Valiev, Marat
2007-01-01
High-level ab-initio equation-of-motion coupled-cluster methods with singles, doubles, and noniterative triples are used, in conjunction with the combined quantum mechanical molecular mechanics approach, to investigate the structure of low-lying excited states of the guanine base in DNA and solvated environments. Our results indicate that while the excitation energy of the first excited state is barely changed compared to its gas-phase counterpart, the excitation energy of the second excited state is blue-shifted by 0.24 eV.
NASA Astrophysics Data System (ADS)
Tabar, Emre; Yakut, Hakan; Kuliev, Ali Akbar
2016-07-01
The ground state magnetic moments and the low-lying magnetic dipole (Ml) transitions from the ground to excited states in heavy deformed odd-mass 181Ta have been microscopically investigated on the basis of the quasiparticle-phonon nuclear model (QPNM). The problem of the spurious state mixing in M1 excitations is overcome by a restoration method allowing a self-consistent determination of the separable effective restoration forces. Due to the self-consistency of the method, these effective forces contain no arbitrary parameters. The results of calculations are compared with the available experimental data, the agreement being reasonably satisfactory.
Guo, Jin-Chang; Hou, Gaolei; Li, Si-Dian; Wang, Xue B.
2012-02-02
Despite a seemingly simple appearance, cyclobutanetetraone (C{sub 4}O{sub 4}) has four low-lying electronic states. Determining the energetic ordering of these states and the ground state of C{sub 4}O{sub 4}{sup -} theoretically has been proven to be considerably challenging and remains largely unresolved to date. Here we report a low-temperature negative ion photoelectron spectroscopic approach. A well structured spectrum with evenly spaced features was obtained at 193 nm due to excitation of the ring breathing mode of the C{sub 4}O{sub 4} neutral, whereas each 193-nm feature was observed to further split into a three-peak manifold at 266 nm assigned due to three electronic transitions from the ground state of the anion to the ground and two low-lying excited states of the neutral. Combined with recent theoretical studies and our own Franck-Condon factors simulations, the ground state of C{sub 4}O{sub 4}{sup -}, as well as the ground and two low-lying excited states of C{sub 4}O{sub 4} are determined to be {sup 2}A{sub 2u}, and {sup 3}B{sub 2u}, {sup 1}A{sub 1g} (8{pi}), {sup 1}B{sub 2u}, respectively. The frequency of the ring breathing mode (1810 {+-} 20 cm{sup -1}), the electron affinity (3.475 {+-} 0.005 eV), and the term values of {sup 1}A{sub 1g} (8{pi}) (6.27 {+-} 0.5 kJ/mol) and {sup 1}B{sub 2u} (13.50 {+-} 0.5 kJ/mol) are also directly obtained from the experiments.
Muller, H. S.; Brown, Linda R.; Drouin, B. J.; Pearson, J. C.; Kleiner, Isabelle; Sams, Robert L.; Sung, Keeyoon; Ordu, Matthias H.; Lewen, Frank
2015-06-01
Rotational and rovibrational spectra of methyl cyanide were recorded to analyze interactions in low-lying vibrational states and to construct line lists for radio astronomical observations as well as for infrared spectroscopic investigations of planetary atmospheres. The rotational spectra cover large portions of the 36-1627 GHz region. In the infrared (IR), a spectrum was recorded for this study in the region of 2v(8) around 717 cm(-1) with assignments covering 684-765 cm-1. Additional spectra in the vs region were used to validate the analysis.
Theoretical spectroscopy study of the low-lying electronic states of UX and UX^{+}, X = F and Cl
Bross, David H.; Peterson, Kirk A.
2015-11-13
Spectroscopic constants (T_{e}, r_{e}, B_{0}, ω_{e}, ω_{e}x_{e}) have been calculated for the low-lying electronic states of UF, UF^{+}, UCl, and UCl^{+} using complete active space 2nd-order perturbation theory (CASPT2), with a series of correlation consistent basis sets. The latter included those based on both pseudopotential (PP) and all-electron Douglas-Kroll-Hess (DK) Hamiltonians for the U atom. Spin orbit effects were included a posteri using the state interacting method using both PP and Breit Pauli (BP) operators, as well as from exact two-component (X2C) methods for U^{+} and UF^{+}. Complete basis set (CBS) limits were obtained by extrapolation where possible and the PP and BP calculations were compared at their respective CBS limits. The PP-based method was shown to be reliable in calculating spectroscopic constants, in particular when using the state interacting method with CASPT2 energies (SO-CASPT2). The two component calculations were limited by computational resources and could not include electron correlation from the nominally closed shell 6s and 6p orbitals of U. UF and UCl were both calculated to have Ω=9/2 ground states. The first excited state of UCl was calculated to be an Ω=7/2 state at 78 cm^{-1} as opposed to the same state at 435 cm-1 in UF, and the other low-lying states of UCl showed a similar compression relative to UF. Likewise UF+ and UCl+ both have Ω=4 ground states and the manifold of low-lying excited Ω = 3, 2, 1, 0 states were energetically closer together in UCl^{+} than in UF^{+}, ranging up to 776 cm^{-1} in UF^{+} and only 438 cm^{-1} in UCl^{+}. As in previous research, the final PP-based SO-CASPT2 results for UF^{+} and UF agree well with experiment, and are expected to be predictive for UCl and UCl^{+}, which are reported here for the first time.
NASA Astrophysics Data System (ADS)
Yuan, Jian-Hui; Zhang, Yan; Guo, Xinxia; Zhang, Jinjin; Mo, Hua
2015-04-01
Using the configuration-integration method, we investigated theoretically the low-lying states and optical absorption properties of a hydrogenic impurity in a parabolic quantum dot modulation by applied electric field. The low-lying states and optical absorption properties depend sensitively on the electric field F and the strength of the parabolic confinement ℏω0 . We discuss the linear and third-order nonlinear optical absorption coefficients of the dot (i) with the impurity ion and (ii) without the impurity ion. In the first case, the increase of the parabolic confinement ℏω0 (or the electric field F) can induce the blueshift (or redshift) of the peak of the absorption coefficient. Also the optical intensity can induce the increase of the third-order nonlinear optical absorption coefficients to weaken and even bleach the total optical absorption coefficients. Similar behavior has also been observed in the second case, but there is no redshift of the peak positions of the absorption coefficient with the increase of the electric field F. Compared with the second case, it is easily seen that there are the blueshifts of the peak of the absorption coefficients, which can be used as a technical means for detecting impurities.
NASA Astrophysics Data System (ADS)
Zhang, Xiaomei; Liu, Xiaoting; Liang, Guiying; Li, Rui; Xu, Haifeng; Yan, Bing
2016-01-01
The potential energy curves (PECs) of the 22 Λ-S states of the phosphorus monoiodide (PI) molecule have been calculated at the level of MRCI+Q method with correlation-consistent quadruple-ζ quality basis set. The spectroscopic constants of the bound states are determined, which well reproduce the available measurements. The metastable a1Δ state has been reported for the first time, which lies between the X3Σ- and b1Σ+ states and have much deeper well than the ground state. The R-dependent spin-orbit (SO) matrix elements are calculated with the full-electron Breit-Pauli operator. Based on the SO matrix elements, the perturbations that the 23Π state may suffer from are analyzed in detail. The SOC effect makes the original Λ-S states split into 51 Ω states. In the zero-field splitting of the ground state X3Σ-, the spin-spin coupling contribution (2.23 cm-1) is found to be much smaller compared to the spin-orbit coupling contribution (50 cm-1). The avoided crossings between the Ω states lead to much shallower potential wells and the change of dissociation relationships of the states. The Ω-state wavefunctions are analyzed depending on their Λ-S compositions, showing the strong interactions among several quasidegenerate Λ-S states of the same total SO symmetry. The transition properties including electric dipole (E1), magnetic dipole (M1), and electric quadrupole (E2) transition moments (TMs), the Franck-Condon factors, the transition probabilities and the radiative lifetimes are computed for the transitions between Ω components of a1Δ and b1Σ+ states and ground state. The transition probabilities induced by the E1, E2, and M1 transitions are evaluated. The E2 makes little effect on transition probabilities. In contrast, the E1 transition makes the main contribution to the transition probability and the M1 transition also brings the influence that cannot be neglected. Finally, the radiative lifetimes are determined with the transition moments including E
NASA Astrophysics Data System (ADS)
Wang, Xinxin; Shi, Deheng; Sun, Jinfeng; Zhu, Zunlue
2015-02-01
The spectroscopic properties are in detail studied for the 11Σ-, 21Σ-, b1Σ+, c1Π, 21Π, 31Π, a1Δ, 21Δ, X3Σ-, C3Σ-, 33Σ-, 13Σ+, A3Π, B3Π, 33Π, 13Δ, 23Δ, 15Σ- and 15Π states, which are yielded from the first two dissociation limits, P(4Su) + Cl(2Pu) and P(2Du) + Cl(2Pu), of the PCl radical. Of the nineteen states, the 33Σ-, 13Σ+, 13Δ, 23Δ and 15Π states are the repulsive ones. The 21Σ-, 21Δ and 15Σ- states and the second well of A3Π state are very weakly-bound ones. The A3Π and B3Π states, the B3Π and 33Π states, and the 21Π and 31Π states have the avoided crossings. The A3Π state is found to possess the double well. The potential energy curves (PECs) are calculated with the CASSCF method followed by the internally contracted MRCI approach with Davidson correction together with the Dunning's correlation-consistent basis sets, aug-cc-pV6Z. To improve the quality of PECs, core-valence correlation and scalar relativistic correction calculations are included simultaneously. The PECs are extrapolated to the complete basis set limit. The vibrational properties are evaluated for several weakly-bound states. The spectroscopic parameters are determined, and compared with those available in the literature. The Franck-Condon factors and radiative lifetimes of the transitions from the A3Π, B3Π and 33Π states to the X3Σ- state and from the c1Π, 21Π and 31Π states to the a1Δ state are calculated for several low vibrational states. And some necessary discussion is performed. Analyses demonstrate that the spectroscopic properties of PCl radical reported in this paper can be expected to be reliably predicted ones.
Blum, H; Salerno, J C; Prince, R C; Leigh, J S; Ohnishi, T
1977-01-01
The temperature dependence of the EPR spectrum of oxidized high-potential iron protein from Chromatium vinosum has been studied. From line width and intensity measurements it is possible to determine the position of the first excited unoccupied state, 160 +/- 10 cm-1 above the ground state orbital. PMID:198036
Coto, Pedro B; Sharifzadeh, Sahar; Neaton, Jeffrey B; Thoss, Michael
2015-01-13
The lowest-lying electronic excited states of pentacene and its oligomers are investigated using accurate multireference wave function methods (CASPT2/CASSCF) and the many-body Greens's function approach (GW/BSE). The results obtained for dimers and trimers of different geometry reveal a complex electronic structure, which includes locally excited, charge transfer, and multiexciton states. For singlets of single-excitation character, both approaches yield excitation energies that are in good overall quantitative agreement. While the multiexciton states are located relatively high in energy in all systems investigated, charge transfer states exist in close proximity to the lowest-lying absorbing states. The implications of the results for the mechanisms of singlet fission in pentacene are discussed. PMID:26574213
Theoretical study of the low-lying electronic states of ZnO and ZnS
NASA Technical Reports Server (NTRS)
Bauschlicher, C. W., Jr.; Langhoff, S. R.
1986-01-01
Theoretical spectroscopic constants and dipole moments are determined for the 1 Sigma(+), 1,3 Pi, and 3 Sigma(+) states of ZnO and ZnS, using extended Gaussian basis sets and incorporating correlation using both configuration-interaction and coupled pair (CPF) methods. Relativistic corrections (Darwin plus mass velocity), included using first-order perturbation theory, are relatively small. At the CPF level, both ZnO and ZnS have 1 Sigma(+) ground states, with the 3 Pi state lying 209 and 2075/cm higher, respectively. The 3 Sigma(+) state lies about 1.5 eV higher in ZnO and 2.1 eV higher in ZnS. The 1,3 Pi states are relatively close together since the exchange splitting is small with the sigma electron localized on Zn and the pi electron on oxygen (or sulfur).
Christensen, Ronald L.; Enriquez, Miriam M.; Wagner, Nicole L.; Peacock-Villada, Alexandra Y.; Scriban, Corina; Schrock, Richard R.; Polívka, Tomáš; Frank, Harry A.; Birge, Robert R.
2013-01-01
Steady-state and ultrafast transient absorption spectra were obtained for a series of conformationally-constrained, isomerically pure polyenes with 5–23 conjugated double bonds (N). These data and fluorescence spectra of the shorter polyenes reveal the N dependence of the energies of six 1Bu+ and two 1Ag− excited states. The 1Bu+ states converge to a common infinite polyene limit of 15,900 ± 100 cm−1. The two excited 1Ag− states, on the other hand, exhibit a large (~9000 cm−1) energy difference in the infinite polyene limit, in contrast to the common value previously predicted by theory. EOM-CCSD ab-initio and MNDO-PSDCI semi-empirical MO theories account for the experimental transition energies and intensities. The complex, multistep dynamics of the 11Bu+ → 21Ag− → 11Ag− excited state decay pathways as a function of N are compared with kinetic data from several natural and synthetic carotenoids. Distinctive transient absorption signals in the visible region, previously identified with S* states in carotenoids, also are observed for the longer polyenes. Analysis of the lifetimes of the 21Ag− states, using the energy gap law for nonradiative decay, reveals remarkable similarities in the N dependence of the 21Ag− decay kinetics of the carotenoid and polyene systems. These findings are important for understanding the mechanisms by which carotenoids carry out their roles as light-harvesting molecules and photoprotective agents in biological systems. PMID:23330819
NASA Astrophysics Data System (ADS)
Barker, Beau; Meyer, Edmund; Schacht, Mike; Collins, Lee; Wilkerson, Marianne; Zhao, Xinxin
2016-05-01
The low-lying (7.8 eV) isomeric state in 229 Th has the potential to become a nuclear frequency standard. 229 Th recoils from 233 U decays have been collected in MgF2 for use in the direct search of the transition. Of interest is the oxidation state of the implanted 229 Th atoms as this can have an influence on the decay mechanisms and photon emission rate. Too determine the oxidation state of the implanted 229 Th recoils we have employed laser induced florescence (LIF), and plan-wave pseudopotential DFT calculations to search for emission from thorium ions in oxidation states less than + 4. Our search focused on detecting emission from Th3+ ions. The DFT calculations predicted the Th3+ state to be the most likely to be present in the crystal after Th4+. We also calculated the band structure for the Th3+ doped MgF2 crystal. For LIF spectra a number of excitation wavelengths were employed, emission spectra in the visible to near-IR were recorded along with time-resolved emission spectra. We have found no evidence for Th3+ in the MgF2 plates. We also analyzed the detection limit of our apprentice and found that the minimum number of Th3+ atoms that we could detect is quite small compared to the number of implanted 229 Th recoils. The number of implanted 229 Th recoils was derived from a γ-ray spectrum by monitoring emission from the daughters of 228 Th. These were present in the MgF2 plates due to a 232 U impurity, which decays to 228 Th, in the source. LA-UR-16-20442.
NASA Astrophysics Data System (ADS)
Hermoso, Willian; Ornellas, Fernando R.
2012-03-01
All doublet and quartet electronic states correlating with the first dissociation channel of SeCl and some Rydberg states are investigated theoretically at the CASSCF/MRCI level of theory using extended basis sets, including the contribution of spin-orbit effects. The similarity of the potential energy curves with those of SeF suggests that spectroscopic constants for the ground (X 2Π) and the first excited quartet (a4Σ-) of SeCl could also be determined via an emission resulting from the reaction of selenium with atomic chlorine. The coupling constant of the ground state at Re is estimated as -1610 cm-1. The potential energy curves calculated and the derived spectroscopic constants do not support the interpretation and assignment of the scarce transitions recorded experimentally as due to 2Π-2Π emissions. That the few observed lines might arise from transitions from the state b4∑1/2- to a very high vibrational level of the state a4∑1/2- is an open possibility, however, the number of vibrational states and the calculated ΔG1/2 differ significantly from the reported ones.
NASA Astrophysics Data System (ADS)
Qin, X.; Zhang, S. D.
2014-12-01
The six doublet and the two quartet electronic states (2Σ+(2), 2Σ-, 2Π(2), 2Δ, 4Σ-, and 4Π) of the OH radical have been studied using the multi-reference configuration interaction (MRCI) method where the Davidson correction, core-valence interaction and relativistic effect are considered with large basis sets of aug-cc-pv5z, aug-cc-pcv5z, and cc-pv5z-DK, respectively. Potential energy curves (PECs) and dipole moment functions are also calculated for these states for internuclear distances ranging from 0.05 nm to 0.80 nm. All possible vibrational levels and rotational constants for the bound state X2Π and A2Σ+ of OH are predicted by numerical solving the radial Schrödinger equation through the Level program, and spectroscopic parameters, which are in good agreements with experimental results, are obtained. Transition dipole moments between the ground state X2Π and other excited states are also computed using MRCI, and the transition probability, lifetime, and Franck-Condon factors for the A2Σ+-X2Π transition are discussed and compared with existing experimental values.
Isospin Character of Low-Lying Pygmy Dipole States in Pb208 via Inelastic Scattering of O17 Ions
NASA Astrophysics Data System (ADS)
Crespi, F. C. L.; Bracco, A.; Nicolini, R.; Mengoni, D.; Pellegri, L.; Lanza, E. G.; Leoni, S.; Maj, A.; Kmiecik, M.; Avigo, R.; Benzoni, G.; Blasi, N.; Boiano, C.; Bottoni, S.; Brambilla, S.; Camera, F.; Ceruti, S.; Giaz, A.; Million, B.; Morales, A. I.; Vandone, V.; Wieland, O.; Bednarczyk, P.; Ciemała, M.; Grebosz, J.; Krzysiek, M.; Mazurek, K.; Zieblinski, M.; Bazzacco, D.; Bellato, M.; Birkenbach, B.; Bortolato, D.; Calore, E.; Cederwall, B.; Charles, L.; de Angelis, G.; Désesquelles, P.; Eberth, J.; Farnea, E.; Gadea, A.; Görgen, A.; Gottardo, A.; Isocrate, R.; Jolie, J.; Jungclaus, A.; Karkour, N.; Korten, W.; Menegazzo, R.; Michelagnoli, C.; Molini, P.; Napoli, D. R.; Pullia, A.; Recchia, F.; Reiter, P.; Rosso, D.; Sahin, E.; Salsac, M. D.; Siebeck, B.; Siem, S.; Simpson, J.; Söderström, P.-A.; Stezowski, O.; Theisen, Ch.; Ur, C.; Valiente-Dobón, J. J.
2014-07-01
The properties of pygmy dipole states in Pb208 were investigated using the Pb208(O17, O17'γ) reaction at 340 MeV and measuring the γ decay with high resolution with the AGATA demonstrator array. Cross sections and angular distributions of the emitted γ rays and of the scattered particles were measured. The results are compared with (γ, γ') and (p, p') data. The data analysis with the distorted wave Born approximation approach gives a good description of the elastic scattering and of the inelastic excitation of the 2+ and 3- states. For the dipole transitions a form factor obtained by folding a microscopically calculated transition density was used for the first time. This has allowed us to extract the isoscalar component of the 1- excited states from 4 to 8 MeV.
An Ab Initio Study of the Low-Lying Doublet States of AgO and AgS
NASA Technical Reports Server (NTRS)
Bauschlicher, Charles W., Jr.; Partridge, Harry; Langhoff, Stephen R.
1990-01-01
Spectroscopic constants (D(sub o), r(sub e), mu(sub e), T(sub e)) are determined for the doublet states of AgO and AgS below approx. = 30000/cm. Large valence basis sets are employed in conjunction with relativistic effective core potentials (RECPs). Electron correlation is included using the modified coupled-pair functional (MCPF) and multireference configuration interaction (MRCI) methods. The A(sup 2)Sigma(sup +) - X(sup 2)Pi band system is found to occur in the near infrared (approx. = 9000/cm) and to be relatively weak with a radiative lifetime of 900 microns for A(sup 2)Sigma(sup +) (upsilon = 0). The weakly bound C(sup 2)Pi state (our notation), the upper state of the blue system, is found to require high levels of theoretical treatment to determine a quantitatively accurate potential. The red system is assigned as a transition from the C(sup 2)Pi state to the previously unobserved A(sup 2)Sigma(sup +) state. Several additional transitions are identified that should be detectable experimentally. A more limited study is performed for the vertical excitation spectrum of AgS. In addition, a detailed all-electron study of the X(sup 2)Pi and A(sup 2)Sigma(sup +) states of AgO is carried out using large atomic natural orbital (ANO) basis sets. Our best calculated D(sub o) value for AgO is significantly less than the experimental value, which suggests that there may be some systematic error in the experimental determination.
NASA Astrophysics Data System (ADS)
Wang, Jie-Min; Liu, Qiang
2013-09-01
The potential energy curves (PECs) of four electronic states (X1Σg+, e3Δu, a3Σu-, and d3Πg) of an As2 molecule are investigated employing the complete active space self-consistent field (CASSCF) method followed by the valence internally contracted multireference configuration interaction (MRCI) approach in conjunction with the correlation-consistent aug-cc-pV5Z basis set. The effect on PECs by the relativistic correction is taken into account. The way to consider the relativistic correction is to employ the second-order Douglas-Kroll Hamiltonian approximation. The correction is made at the level of a cc-pV5Z basis set. The PECs of the electronic states involved are extrapolated to the complete basis set limit. With the PECs, the spectroscopic parameters (Te, Re, ωe, ωexe, ωeye, αe, βe, γe, and Be) of these electronic states are determined and compared in detail with those reported in the literature. Excellent agreement is found between the present results and the experimental data. The first 40 vibrational states are studied for each electronic state when the rotational quantum number J equals zero. In addition, the vibrational levels, inertial rotation and centrifugal distortion constants of d3Πg electronic state are reported which are in excellent agreement with the available measurements. Comparison with the experimental data shows that the present results are both reliable and accurate.
NASA Astrophysics Data System (ADS)
Wang, Peng; Nakamura, Ryosuke; Kanematsu, Yasuo; Koyama, Yasushi; Nagae, Hiroyoshi; Nishio, Tomohiro; Hashimoto, Hideki; Zhang, Jian-Ping
2005-07-01
Electronic absorption spectra were recorded at room temperature in solutions of carotenoids having different numbers of conjugated double bonds, n = 8-13, including a spheroidene derivatives, neurosporene, spheroidene, lycopene, anhydrorhodovibrin and spirilloxanthin. The vibronic states of 1Bu+(v=0-4), 2Ag-(v=0-3), 3Ag- (0) and 1Bu- (0) were clearly identified. The arrangement of the four electronic states determined by electronic absorption spectroscopy was identical to that determined by measurement of resonance Raman excitation profiles [K. Furuichi et al., Chem. Phys. Lett. 356 (2002) 547] for carotenoids in crystals.
Matrix elements in the coupled-cluster approach - With application to low-lying states in Li
NASA Technical Reports Server (NTRS)
Martensson-Pendrill, Ann-Marie; Ynnerman, Anders
1990-01-01
A procedure is suggested for evaluating matrix elements of an operator between wavefunctions in the coupled-cluster form. The use of the exponential ansatz leads to compact exponential expressions also for matrix elements. Algorithms are developed for summing all effects of one-particle clusters and certain chains of two-particle clusters (containing the well-known random-phase approximation as a subset). The treatment of one-particle perturbations in single valence states is investigated in detail. As examples the oscillator strength for the 2s-2p transition in Li as well as the hyperfine structure for the two states are studied and compared to earlier work.
NASA Astrophysics Data System (ADS)
Miyashita, Yuji; Ouchi, Hiroyuki; Izumi, Sayaka; Sasaki, Ayako; Sato, Nozomi; Tateoka, Miki; Hoshino, Sayo; Nagano, Tetsuya; Yamashita, Wataru; Yamazaki, Akiyoshi; Shimada, Kenzi; Ishida, Takashi; Wakui, Takashi; Shinozuka, Tsutomu; Tanigaki, Minoru
2009-10-01
To extend the studies on neutron-rich nuclei, we have developed an RF-IGISOL technique, which is combination of the gas catcher technique and the electrical field guiding technique with a large volume gas cell. As the first step to such approach, we are planning and trying the systematic measurement of g-factor in the neutron rich nuclei extracted as an radioactive beam from our RF-IGISOL at Tohoku University. The g-factor measurement for the low-lying state of ^109Rh (Ex = 225.98 keV, T1/2 = 1.66 μs) is the first on-line experiment with our RF-IGISOL system. The g-factor for this state has been determined to be g = 0.78 ^+0.17-0.03 μN by the on-line TDPAC method. In this contribution, the details of experimental results will be reported.
Langhoff, S.R.; Pettersson, L.G.M.; Bauschlicher C.W. Jr.; Partridge, H.
1987-01-01
Spectroscopic parameters (D/sub e/,r/sub e/,..mu../sub e/) are determined for the second-row transition metal hydrides using large valence basis sets in conjunction with relativistic effective core potentials (RECPs). All-electron calculations are also performed for YH and AgH to calibrate the RECP results. Electron correlation is incorporated using singles-plus-doubles configuration interaction (SDCI), the coupled pair functional (CPF) method, and a modified version (MCPF) of CPF. Although similarities exist between the bonding in the first- and second-row transition metal hydrides, the greater overlap of the d orbitals in the second row with the hydrogen 1s orbital, tends to lead to larger dissociation energies and some changes in the relative ordering of the states. For example, the ground state of ZrH is predicted to be a /sup 2/..delta.. state whose bonding involves 4d--5s hybrid orbitals, whereas in TiH the ground state is a /sup 4/Phi state with primarily 4s--1s bonding. The bonding in the second-row transition metal hydrides involves a mixture of all three atomic asymptotes, 4d/sup n/5s/sup 2/, 4d/sup n//sup +1/5s/sup 1/, and 4d/sup n//sup +2/, whereas contribution from the 3d/sup n//sup +2/ asymptote is unimportant in the first-row TM hydrides. However, the bonding is generally much simpler to describe in the second-row as compared with the first-row TM hydrides, and the spectroscopic parameters are much less sensitive to the level of correlation treatment.
Structure of low-lying states of {sup 10,11}C from proton elastic and inelastic scattering
Jouanne, C.; Lapoux, V.; Auger, F.; Alamanos, N.; Drouart, A.; Gillibert, A.; Lobo, G.; Musumarra, A.; Nalpas, L.; Pollacco, E.; Sida, J.-L.; Trotta, M.; Blumenfeld, Y.; Khan, E.; Suomijaervi, T.; Zerguerras, T.; Roussel-Chomaz, P.; Savajols, H.; Lagoyannis, A.; Pakou, A.
2005-07-01
To probe the ground state and transition densities, elastic and inelastic scattering on a proton target were measured in inverse kinematics for the unstable {sup 10}C and {sup 11}C nuclei at 45.3 and 40.6 MeV/nucleon, respectively. The detection of the recoil proton was performed by the MUST telescope array, in coincidence with a wall of scintillators for the quasiprojectile. The differential cross sections for elastic and inelastic scattering to the first excited states are compared to the optical model calculations performed within the framework of the microscopic nucleon-nucleus Jeukenne-Lejeune-Mahaux potential. Elastic scattering is sensitive to the matter-root-mean square radius found to be 2.42{+-}0.1 and 2.33{+-}0.1 fm, for {sup 10,11}C, respectively. The transition densities from cluster and mean-field models are tested, and the cluster model predicts the correct order of magnitude of cross sections for the transitions of both isotopes. Using the Bohr-Mottelson prescription, a profile for the {sup 10}C transition density from the 0{sup +} ground to the 2{sub 1}{sup +} state is deduced from the data. The corresponding neutron transition matrix element is extracted: M{sub n}=5.51{+-}1.09 fm{sup 2}.
All-electron first principles calculations of the ground and some low-lying excited states of BaI.
Miliordos, Evangelos; Papakondylis, Aristotle; Tsekouras, Athanasios A; Mavridis, Aristides
2007-10-01
The electronic structure of the heavy diatomic molecule BaI has been examined for the first time by ab initio multiconfigurational configuration interaction (MRCI) and coupled cluster (RCCSD(T)) methods. The effects of special relativity have been taken into account through the second-order Douglas-Kroll-Hess approximation. The construction of Omega(omega,omega) potential energy curves allows for the estimation of "experimental" dissociation energies (De) of the first few excited states by exploiting the accurately known De experimental value of the X2Sigma+ ground state. All states examined are of ionic character with a Mulliken charge transfer of 0.5 e- from Ba to I, and this is reflected to large dipole moments ranging from 6 to 11 D. Despite the inherent difficulties of a heavy system like BaI, our results are encouraging. With the exception of bond distances that on the average are calculated 0.05 A longer than the experimental ones, common spectroscopic parameters are in fair agreement with experiment, whereas De values are on the average 10 kcal/mol smaller. PMID:17850123
NASA Astrophysics Data System (ADS)
Liu, Hui; Shi, Deheng; Sun, Jinfeng; Zhu, Zunlue
2014-05-01
Using the CASSCF method followed by the internally contracted MRCI approach in combination with the correlation-consistent basis sets, the potential energy curves (PECs) are calculated for the X3Π, A3Σ-, B3Σ+, C3Π, E3Δ, a1Σ+, b1Π, c1Δ, d1Σ+, e1Π, 23Σ- and 33Σ- electronic states of AlN molecule for internuclear separations from 0.1 to 1.0 nm. All the electronic states correlate to the three dissociation channels, Al(2Pu) + N(4Su), Al(2Pu) + N(2Du) and Al(2Pu) + N(2Pu). Of these 12 electronic states, only the 23Σ- possesses the double well. The PECs determined by the internally contracted MRCI approach are corrected for size-extensivity errors by means of the Davidson correction. The convergent behavior of present calculations is observed with respect to the basis set and level of theory. The effect of core-valence correlation and scalar relativistic corrections on the spectroscopic parameters is discussed. Scalar relativistic correction calculations are performed by the third-order Douglas-Kroll Hamiltonian approximation at the level of cc-pVTZ basis set. Core-valence correlation corrections are included with a cc-pCVTZ basis set. All the PECs are extrapolated to the complete basis set limit. The spectroscopic parameters are evaluated by fitting the first ten vibrational levels when available, which are obtained by solving the ro-vibrational Schrödinger equation with the Numerov's method. The spectroscopic parameters are compared with those reported in the literature. Excellent agreement is found between the present results and the measurements. Analyses show that the spectroscopic parameters reported in this paper can be expected to be reliably predicted ones. The Franck-Condon factors and radiative lifetimes of the transitions from the A3Σ-, B3Σ+, C3Π, a1Σ+ and b1Π electronic states to the ground state are calculated for several low vibrational levels, and some necessary discussion has been made.
NASA Astrophysics Data System (ADS)
Marwa, N. El-Hammamy
2015-03-01
The experimental data on elastic and inelastic scattering of 270 MeV 3He particles to several low lying states in 90Zr, 116Sn and 208Pb are analyzed within the double folding model (DFM). Fermi density distribution (FDD) of target nuclei is used to obtain real potentials with different powers. DF results are introduced into a modified DWUCK4 code to calculate the elastic and inelastic scattering cross sections. Two choices of potentials form factors are used; Woods Saxon (WS) and Woods Saxon Squared (WS2) for real potential, while the imaginary part is taken as phenomenological Woods Saxon (PWS) and phenomenological Woods Saxon Squared (PWS2). This comparison provides information about the similarities and differences of the models used in calculations.
Xie Wenfang
2013-01-31
Optical absorptions of the low-lying states with higher angular momenta of the D{sup -} system in a spherical quantum dot (QD) with the Gaussian potential are studied by using the matrix diagonalisation method and the compact density-matrix approach. The linear, nonlinear third-order and total optical absorption coefficients are calculated for the {sup 1}P{sup -} {yields} {sup 1}D{sup +} and {sup 1}D{sup +} {yields} {sup 1}F{sup -} transitions. Numerical results for GaAs/Ga{sub 1-x}Al{sub x}As QDs are presented. The calculated results show that with increasing quantum numbers describing the angular momenta of transitions the optical absorption peaks shift towards lower energies and their intensities increase. (quantum dots)
NASA Astrophysics Data System (ADS)
Koh, Yang Wei
2016-04-01
We present an extensive numerical study of the Sherrington-Kirkpatrick model in a transverse field. Recent numerical studies of quantum spin glasses have focused on exact diagonalization of the full Hamiltonian for small systems (≈20 spins). However, such exact numerical treatments are difficult to apply on larger systems. We propose making an approximation by using only a subspace of the full Hilbert space spanned by low-lying excitations consisting of one-spin-flipped and two-spin-flipped states. The approximation procedure is carried out within the theoretical framework of the Hartree-Fock approximation and configuration interaction. Although not exact, our approach allows us to study larger system sizes comparable to that achievable by state-of-the-art quantum Monte Carlo simulations. We calculate two quantities of interest due to recent advances in quantum annealing, the ground-state energy and the energy gap between the ground and first excited states. For the energy gap, we derive a formula that enables it to be calculated using just the ground-state wave function, thereby circumventing the need to diagonalize the Hamiltonian. We calculate the scalings of the energy gap and the leading correction to the extensive part of the ground-state energy with system size, which are difficult to obtain with current methods.
Li, Xia; Zhang, Xiaomei; Yan, Bing
2015-05-01
Ab initio calculations have been performed on the low-lying excited and ground states of PH(+). The potential energy curves (PECs) of the Λ-S states were calculated with multi-reference configuration interaction (MRCI) method along with the basis sets at 5-ξ level. In order to improve the PECs, the Davidson(+Q) correction and the Scalar relativistic effect are included. The corresponding spectroscopic constants were determined and good agreements with the available measurement were found. The interactions of the A(2)Δ-(4)Π and 1(2)Σ(+)-(4)Π by the spin-orbit coupling (SOC) effect were well described by the spin-orbit matrix elements. The SOC effect makes the original 8 Λ-S states split into 15Ω states. The Ω=1/2 state generated from the X(2)Π state is confirmed to the ground Ω state. And the SOC splitting for the X(2)Π is calculated to be 294cm(-1). The SOC effect has large effect on the PECs of the A(2)Δ and 1(2)Σ(+) states, leading to much more shallow potential wells as well as potential barriers. The analysis of the wavefunction for the Ω states shows that the strong spin-orbit interaction exists near the crossing points of the PECs for the Λ-S states. The transition dipole moments (TDMs) of transitions A(2)Δ-X(2)Π and 1(2)Σ(-)-X(2)Π are evaluated with the MRCI wavefunction. Based on the TDMs along with the calculated Franck-Condon factors, the radiative lifetimes for the selected vibrational levels of A(2)Δ and 1(2)Σ(-) states are predicted at the microseconds (μs). Good agreement with the measurement shows that the lowest vibrational level for A(2)Δ state is almost uninfluenced by the perturbation via the SOC effect. PMID:25688687
NASA Astrophysics Data System (ADS)
Li, Xia; Zhang, Xiaomei; Yan, Bing
2015-05-01
Ab initio calculations have been performed on the low-lying excited and ground states of PH+. The potential energy curves (PECs) of the Λ-S states were calculated with multi-reference configuration interaction (MRCI) method along with the basis sets at 5-ξ level. In order to improve the PECs, the Davidson(+Q) correction and the Scalar relativistic effect are included. The corresponding spectroscopic constants were determined and good agreements with the available measurement were found. The interactions of the A2Δ-4Π and 12Σ+-4Π by the spin-orbit coupling (SOC) effect were well described by the spin-orbit matrix elements. The SOC effect makes the original 8 Λ-S states split into 15 Ω states. The Ω = 1/2 state generated from the X2Π state is confirmed to the ground Ω state. And the SOC splitting for the X2Π is calculated to be 294 cm-1. The SOC effect has large effect on the PECs of the A2Δ and 12Σ+ states, leading to much more shallow potential wells as well as potential barriers. The analysis of the wavefunction for the Ω states shows that the strong spin-orbit interaction exists near the crossing points of the PECs for the Λ-S states. The transition dipole moments (TDMs) of transitions A2Δ-X2Π and 12Σ--X2Π are evaluated with the MRCI wavefunction. Based on the TDMs along with the calculated Franck-Condon factors, the radiative lifetimes for the selected vibrational levels of A2Δ and 12Σ- states are predicted at the microseconds (μs). Good agreement with the measurement shows that the lowest vibrational level for A2Δ state is almost uninfluenced by the perturbation via the SOC effect.
NASA Astrophysics Data System (ADS)
Shiga, Y.; Yoneda, K.; Steppenbeck, D.; Aoi, N.; Doornenbal, P.; Lee, J.; Liu, H.; Matsushita, M.; Takeuchi, S.; Wang, H.; Baba, H.; Bednarczyk, P.; Dombradi, Zs.; Fulop, Zs.; Go, S.; Hashimoto, T.; Honma, M.; Ideguchi, E.; Ieki, K.; Kobayashi, K.; Kondo, Y.; Minakata, R.; Motobayashi, T.; Nishimura, D.; Otsuka, T.; Otsu, H.; Sakurai, H.; Shimizu, N.; Sohler, D.; Sun, Y.; Tamii, A.; Tanaka, R.; Tian, Z.; Tsunoda, Y.; Vajta, Zs.; Yamamoto, T.; Yang, X.; Yang, Z.; Ye, Y.; Yokoyama, R.; Zenihiro, J.
2016-02-01
The low-lying level structures of nuclei in the vicinity of 78Ni were investigated using in-beam γ -ray spectroscopy to clarify the nature of the nuclear magic numbers Z =28 and N =50 in systems close to the neutron drip line. Nucleon knockout reactions were employed to populate excited states in 80Zn and 82Zn. A candidate for the 41+ level in 80Zn was identified at 1979(30) keV, and the lifetime of this state was estimated to be 136-67+92 ps from a line-shape analysis. Moreover, the energy of the 21+ state in 82Zn is reported to lie at 621(11) keV. The large drop in the 21+ energy at 82Zn indicates the presence of a significant peak in the E (21+) systematics at N =50 . Furthermore, the E (41+) /E (21+) and B (E 2 ;41+→21+) /B (E 2 ;21+→0g.s . +) ratios in 80Zn were deduced to be 1.32 (3 ) and 1 .12-60+80 , respectively. These results imply that 80Zn can be described in terms of two-proton configurations with a 78Ni core and are consistent with a robust N =50 magic number along the Zn isotopic chain. These observations, therefore, indicate a persistent N =50 shell closure in nuclei far from the line of β stability, which in turn suggests a doubly magic structure for 78Ni.
NASA Astrophysics Data System (ADS)
Lee, Edmond P. F.; Mok, Daniel K. W.; Chau, Foo-tim; Dyke, John M.
2006-09-01
Geometry optimization calculations were carried out on the X˜A11 state of SF2 and the X˜B12, ÃA12, B˜B22, C˜B22, D˜A12, and ẼA22 states of SF2+ employing the restricted-spin coupled-cluster single-double plus perturbative triple excitation [RCCSD(T)] method and basis sets of up to the augmented correlation-consistent polarized quintuple-zeta [aug-cc-pV(5+d )Z] quality. Effects of core electron (S 2s22p6 and F 1s2 electrons) correlation and basis set extension to the complete basis set limit on the computed minimum-energy geometries and relative electronic energies (adiabatic and vertical ionization energies) were investigated. RCCSD(T) potential energy functions (PEFs) were calculated for the X˜A11 state of SF2 and the low-lying states of SF2+ listed above employing the aug-cc-pV(5+d )Z and aug-cc-pV5Z basis sets for S and F, respectively. Anharmonic vibrational wave functions of these neutral and cationic states of SF2, and Franck-Condon (FC) factors of the lowest four one-electron allowed neutral photoionizations were computed employing the RCCSD(T) PEFs. Calculated FC factors with allowance for Duschinsky rotation and anharmonicity were used to simulate the first four photoelectron bands of SF2. The agreement between the simulated and observed first bands in the HeI photoelectron spectrum reported by de Leeuw et al. [Chem. Phys. 34, 287 (1978)] is excellent. Our calculations largely support assignments made by de Leeuw et al. on the higher ionization energy bands of SF2.
Peterson, Kirk A.; Francisco, Joseph S.
2014-01-28
A systematic ab initio treatment of the nitryl halides (XNO{sub 2}) and the cis- and trans- conformers of the halide nitrites (XONO), where X = Cl, Br, and I, have been carried out using highly correlated methods with sequences of correlation consistent basis sets. Equilibrium geometries and harmonic frequencies have been accurately calculated in all cases at the explicitly correlated CCSD(T)-F12b level of theory, including the effects of core-valence correlation for the former. Where experimental values are available for the equilibrium structures (ClNO{sub 2} and BrNO{sub 2}), the present calculations are in excellent agreement; however, the X-O distances are slightly too long by about 0.01 Å due to missing multireference effects. Accurate predictions for the iodine species are made for the first time. The vertical electronic excitation spectra have been calculated using equation-of-motion coupled cluster methods for the low-lying singlet states and multireference configuration interaction for both singlet and triplet states. The latter also included the effects of spin-orbit coupling to provide oscillator strengths for the ground state singlet to excited triplet transitions. While for ClNO{sub 2} the transitions to excited singlet states all occur at wavelengths shorter than 310 nm, there is one longer wavelength singlet transition in BrNO{sub 2} and two in the case of INO{sub 2}. The long wavelength tail in the XNO{sub 2} species is predicted to be dominated by transitions to triplet states. In addition to red-shifting from X = Cl to I, the triplet transitions also increase in oscillator strength, becoming comparable to many of the singlet transitions in the case of INO{sub 2}. Hence in particular, the latter species should be very photolabile. Similar trends are observed and reported for the halogen nitrites, many of which for the first time.
NASA Astrophysics Data System (ADS)
Wu, Dong-lan; Tan, Bin; Wen, Yu-feng; Zeng, Xue-feng; Xie, An-dong; Yan, Bing
2016-05-01
Accurate theoretical calculations on the MgBr radical have been carried out by using the high-level relativistic multireference configuration interaction method with Davidson correction (MRCI + Q) using correlation-consistent Quintuple-ζ quality basis set. The potential energy curves (PECs) of the 14 Λ-S states of MgBr have been computed. In order to improve the PECs, the core-valence correlation, scalar relativistic effect, and spin-orbit coupling effect are taken into account in the computations. The spectroscopic constants of the bound states have been determined from the computed PECs. The results of the ground state X2Σ+ and the first excited state A2Π are in good agreement with those from the available experiments, while spectroscopic constants of the other electronic states are firstly reported. The low-lying ion-pair state B2Σ+ correlated to ion-pair dissociation limit Mg+ (2Sg) + Br- (1Sg) is characterized. The permanent dipole moments (PDMs) of Λ-S states and the R-dependent spin-orbit (SO) matrix elements are computed. The results indicate that the abrupt changes of PDMs and the SO matrix elements are attributed to the changes of the electronic configurations near the avoided crossing point. After taking the SOC effect into account, the 14 Λ-S states split into 30 Ω states, and the SOC splitting for the A2Π is calculated to be 102.58 cm- 1. The SOC effect, leading to the double-well potential of the Ω = (3)1/2 state, is found to be substantial for MgBr. In order to further illustrate the SOC effect and the avoided crossing phenomenon of the PECs, the Λ-S compositions in the Ω state wavefunctions are analyzed in detail. Finally, the transition dipole moments (TDMs) of several transitions from upper Ω states to the ground X2Σ+1/2 state and the corresponding radiative lifetimes have been studied. It is shown that the (1)3/2-X2Σ+1/2 and (2)3/2-X2Σ+1/2 are particularly important to the observed transitions A2Π-X2Σ+ and C2Π-X2Σ+. The
Wu, Dong-Lan; Tan, Bin; Wen, Yu-Feng; Zeng, Xue-Feng; Xie, An-Dong; Yan, Bing
2016-05-15
Accurate theoretical calculations on the MgBr radical have been carried out by using the high-level relativistic multireference configuration interaction method with Davidson correction (MRCI+Q) using correlation-consistent Quintuple-ζ quality basis set. The potential energy curves (PECs) of the 14 Λ-S states of MgBr have been computed. In order to improve the PECs, the core-valence correlation, scalar relativistic effect, and spin-orbit coupling effect are taken into account in the computations. The spectroscopic constants of the bound states have been determined from the computed PECs. The results of the ground state X(2)Σ(+) and the first excited state A(2)Π are in good agreement with those from the available experiments, while spectroscopic constants of the other electronic states are firstly reported. The low-lying ion-pair state B(2)Σ(+) correlated to ion-pair dissociation limit Mg(+) ((2)Sg)+Br(-) ((1)Sg) is characterized. The permanent dipole moments (PDMs) of Λ-S states and the R-dependent spin-orbit (SO) matrix elements are computed. The results indicate that the abrupt changes of PDMs and the SO matrix elements are attributed to the changes of the electronic configurations near the avoided crossing point. After taking the SOC effect into account, the 14 Λ-S states split into 30Ω states, and the SOC splitting for the A(2)Π is calculated to be 102.58cm(-1). The SOC effect, leading to the double-well potential of the Ω=(3)1/2 state, is found to be substantial for MgBr. In order to further illustrate the SOC effect and the avoided crossing phenomenon of the PECs, the Λ-S compositions in the Ω state wavefunctions are analyzed in detail. Finally, the transition dipole moments (TDMs) of several transitions from upper Ω states to the ground X(2)Σ(+)1/2 state and the corresponding radiative lifetimes have been studied. It is shown that the (1)3/2-X(2)Σ(+)1/2 and (2)3/2-X(2)Σ(+)1/2 are particularly important to the observed transitions A(2)Π-X(2)
NASA Astrophysics Data System (ADS)
Chattopadhyay, Anjan
2012-02-01
Ab initio-based configuration interaction studies on RbHe and He-Rb-He have explored some key features of the low-lying electronic states of these van der Waals systems. The radiative lifetime of the Rb*He exciplex has been calculated to be around 24.5 ns, which is slightly higher than the HeRb*He lifetime (˜20 ns) and lower than the atomic fluorescence lifetime of Rb, by roughly 3.5 ns. Better exciplex stability of the symmetric triatomic system is evidenced by its higher binding energy value in comparison to the diatomic system by a substantial margin. BSSE-corrected spin-orbit calculations of RbHe have predicted a potential barrier of the 12Π1/2 state with a height of 15 cm-1 and width of 2.57 Å. The 2Πu state of the triatomic molecule shows a conical intersection of its Renner-Teller components (12A1 and 12B2) near a 99° bond angle along the bending path. Their unstable higher excited states (12Σ+1/2 or 12Σ+g,1/2) can trigger the pumping of the blue side of the ns2S1/2 → np2P3/2 transition, and this may eventually lead to the np2P1/2 →ns2S1/2 lasing transition. The broad fluorescence band with a peak near 11 900 cm-1 is found to arise from the 12Π3/2-X2Σ+1/2 transition of RbHe.
NASA Astrophysics Data System (ADS)
Hirano, Tsuneo; Okuda, Rei; Nagashima, Umpei; Jensen, Per
2012-12-01
FeCO is a molecule of astrophysical interest. We report here theoretical calculations of its geometrical parameters, electronic structures, and molecular constants (such as dipole moment and spin-orbit coupling constant) in the electronic ground state tilde{X}3Σ - and the low-lying triplet and quintet excited states. The calculations were made at the MR-SDCI+Q_DK3/[5ZP ANO-RCC (Fe, C, O)] and MR-AQCC_DK3/[5ZP ANO-RCC (Fe, C, O)] levels of theory. A multi-reference calculation was required to describe correctly the wavefunctions of all states studied. For all triplet states, the σ-donation through the 10σ molecular orbital (MO) as well as the π-back-donation through the 4π MO are observed, and the dipole moment vector points from O toward Fe as expected. However, in the excited quintet states 5Π, 5Φ, and 5Δ, the almost negligible contribution of Fe 4s to the 10σ MO makes the dipole moment vector point from Fe toward O, i.e., in the same direction as in CO. In the tilde{X}3Σ - state, the electron provided by the σ-donation through the 10σ MO is shared between the Fe atom and the C end of the CO residue to form a coordinate-covalent Fe-C bond. In the tilde{a}5Σ - state (the high-spin counterpart of tilde{X}3Σ -), the σ-donation through the 10σ MO is not significant and so the Fe-C bond is rather ionic. The π-back-donation through the 4π MO is found to be of comparable importance in the two electronic states; it has a slightly larger magnitude in the tilde{X}3Σ - state. The difference in the molecular properties of the low-spin tilde{X}3Σ - and the high-spin tilde{a}5Σ - states can be understood in terms of the dynamical electron correlation effects.
NASA Astrophysics Data System (ADS)
Mok, Daniel K. W.; Chau, Foo-tim; Lee, Edmond P. F.; Dyke, John M.
2006-09-01
Geometry optimization calculations were carried out on the X˜A11 state of SCl2 and the X˜B12, ÃB22, B˜A12, C˜A12, D˜A22, and ẼB22 states of SCl2+ at the restricted-spin coupled-cluster single-double plus perturbative triple excitation [RCCSD(T)] level with basis sets of up to the augmented correlation-consistent polarized quintuple-zeta [aug-cc-pV(5+d )Z] quality. Effects of core electron correlation, basis set extension to the complete basis set limit, and relativistic contributions on computed minimum-energy geometrical parameters and/or relative electronic energies were also investigated. RCCSD(T) potential energy functions (PEFs) were calculated for the X˜A11 state of SCl2 and the low-lying states of SCl2+ listed above employing the aug-cc-pV(5+d )Z basis set. Anharmonic vibrational wave functions of these neutral and cationic states of SCl2, and Franck-Condon (FC) factors of the lowest four one-electron allowed neutral photoionizations were computed employing the RCCSD(T )/aug-cc-pV(5+d)Z PEFs. Calculated FC factors with allowance for the Duschinsky rotation and anharmonicity were used to simulate the first four photoelectron (PE) bands of SCl2. The agreement between simulated and observed He I PE spectra reported by Colton et al. [J. Electron Spectrosc. Relat. Phenom. 3, 345 (1974)] and Solouki et al. [Chem. Phys. Lett. 26, 20 (1974)] is excellent. However, our FC spectral simulations indicate that the first observed vibrational component in the first PE band of SCl2 is a "hot" band arising from the SCl2+X˜B12(0,0,0)←SCl2X˜A11(1,0,0) ionization. Consequently, the experimental adiabatic ionization energy of SCl2 is revised to 9.55±0.01eV, in excellent agreement with results obtained from state-of-the-art ab initio calculations in this work.
NASA Astrophysics Data System (ADS)
Karamanis, P.; Marchal, R.; Carbonnierre, P.; Pouchan, C.
2012-12-01
The (hyper)polarizabilities of the global minima and of low lying isomers of ground doped aluminum clusters of the AlSin type (n=3-9) have been studied within the density functional framework. Our results show that the polarizabilities and first hyperpolarizabilities per atom of these doped Al doped clusters rabidly degrease with the cluster size. Also by tracing a significant number of stable low lying isomers we demonstrate that both the average values of the mean polarizabilities per atom and of the total fist hyperpolarizabilities of those species follow closely the evolution that is observed in the case of their ground state structures.
NASA Astrophysics Data System (ADS)
Rangel, Tonatiuh; Sharifzadeh, Sahar; Rinn, Andre; da Jornada, Felipe H.; Shao, Meiyue; Witte, Gregor; Yang, Chao; Louie, Steven G.; Chatterjee, Sangaam; Kronik, Leeor; Neaton, Jeffrey B.
Organic semiconductors have attracted attention due to their potential for optoelectronics and novel phenomena, such as singlet fission. Here, we use many-body perturbation theory to simulate neutral excitations in acene and perylene crystals. By diagonalizing the full Bethe-Salpether (BSE) Hamiltonian beyond the Tamm Dancoff approximation (TDA), we find that both low-lying excitation energies and oscillator strengths are in improved agreement with experiments relative to the TDA. We characterize the low-lying excitons, focusing in the degree of charge-transfer and spatial delocalization, connecting their relevance to singlet fission. For perylene, we find overall good agreement with absorption measurements, and we see evidence for the formation of an ``exciton-polariton'' band in β-perylene. This work is supported by the DOE.
NASA Astrophysics Data System (ADS)
Müller, Holger S. P.; Ordu, Matthias H.; Lewen, Frank; Brown, Linda; Drouin, Brian; Pearson, John; Sung, Keeyoon; Kleiner, Isabelle; Sams, Robert
2015-06-01
Rotational and rovibrational spectra of methyl cyanide were recorded to analyze interactions in low-lying vibrational states and to construct line lists for radio astronomical observations as well as for infrared spectroscopic investigations of planetary atmospheres. The rotational spectra cover large portions of the 36-1627~GHz region. In the infrared (IR), a spectrum was recorded for this study in the region of 2ν_8 around 717~cm-1 with assignments covering 684-765~cm-1. Additional spectra in the ν _8 region were used to validate the analysis. Using ν _8 data as well as spectroscopic parameters for v_4 = 1, v_7 = 1, and v_8 = 3 from previous studies, we analyzed rotational data involving v = 0, v_8 = 1, and v_8 = 2 up to high J and K quantum numbers. We analyzed a strong Δ v_8 = ± 1, Δ K = 0, Δ l = ±3 Fermi resonance between v_8 = 1-1 and v_8 = 2+2 at K = 14 and obtained preliminary results for two further Fermi resonances between v_8 = 2 and 3. We also found resonant Δ v_8 = ± 1, Δ K = ∓ 2, Δ l = ± 1 interactions between v_8 = 1 and 2 and present the first detailed analysis of such a resonance between v_8 = 0 and 1. We discuss the impact of this analysis on the v_8 = 1 and 2 as well as on the axial v = 0 parameters and compare selected CH_3CN parameters with those of CH_3CCH and CH_3NC. We evaluated transition dipole moments of ν _8, 2ν _8 - ν _8, and 2ν _8 for remote sensing in the IR. Part of this work was carried out at the Jet Propulsion Laboratory under contract with the National Aeronautics and Space Administration. M. Koivusaari et al., J. Mol. Spectrosc. 152 (1992) 377-388. A.-M. Tolonen et al., J. Mol. Spectrosc. 160 (1993) 554-565.
NASA Astrophysics Data System (ADS)
Yao, J. M.; Engel, J.
2016-07-01
We present a generator-coordinate calculation, based on a relativistic energy-density functional, of the low-lying spectra in the isotopes 150Nd and 150Sm and of the nuclear matrix element that governs the neutrinoless double-β decay of the first isotope to the second. We carefully examine the impact of octupole correlations on both nuclear structure and the double-β decay matrix element. Octupole correlations turn out to reduce quadrupole collectivity in both nuclei. Shape fluctuations, however, dilute the effects of octupole deformation on the double-β decay matrix element, so that the overall octupole-induced quenching is only about 7 % .
Beck, Eric V; Brozell, Scott R; Blaudeau, Jean-Philippe; Burggraf, Larry W; Pitzer, Russell M
2009-11-12
Multireference spin-orbit configuration interaction calculations were used to determine the accuracy of 60-, 68-, and 78-electron shape-consistent relativistic effective core potentials (RECPs) for uranium V and VI ground and low-lying excited states. Both 5f(n) and (5f6d)(n), (n = 1, 2) reference spaces were investigated using correlation-consistent double-zeta quality basis sets. Accuracy was assessed against gas-phase experimental spectra. The 68-electron RECP calculations yielded low relative and rms errors and predicted the empirical ordering of states most consistently. PMID:19888778
NASA Astrophysics Data System (ADS)
Morales, A. I.; Benzoni, G.; Watanabe, H.; Nishimura, S.; Browne, F.; Daido, R.; Doornenbal, P.; Fang, Y.; Lorusso, G.; Patel, Z.; Rice, S.; Sinclair, L.; Söderström, P.-A.; Sumikama, T.; Wu, J.; Xu, Z. Y.; Yagi, A.; Yokoyama, R.; Baba, H.; Avigo, R.; Bello Garrote, F. L.; Blasi, N.; Bracco, A.; Camera, F.; Ceruti, S.; Crespi, F. C. L.; de Angelis, G.; Delattre, M.-C.; Dombradi, Zs.; Gottardo, A.; Isobe, T.; Kojouharov, I.; Kurz, N.; Kuti, I.; Matsui, K.; Melon, B.; Mengoni, D.; Miyazaki, T.; Modamio-Hoyborg, V.; Momiyama, S.; Napoli, D. R.; Niikura, M.; Orlandi, R.; Sakurai, H.; Sahin, E.; Sohler, D.; Shaffner, H.; Taniuchi, R.; Taprogge, J.; Vajta, Zs.; Valiente-Dobón, J. J.; Wieland, O.; Yalcinkaya, M.
2016-03-01
Low-lying excited states in 72Ni have been investigated in an in-flight fission experiment at the RIBF facility of the RIKEN Nishina Center. The combination of the state-of-the-art BigRIPS and EURICA setups has allowed for a very accurate study of the β decay from 72Co to 72Ni, and has provided first experimental information on the decay sequence 72Fe→72Co→72Ni and on the delayed neutron-emission branch 73Co→72Ni . Accordingly, we report nearly 60 previously unobserved γ transitions which deexcite 21 new levels in 72Ni. Evidence for the location of the so-sought-after (42+) ,(62+) , and (81+) seniority states is provided. As well, the existence of a low-spin β -decaying isomer in odd-odd neutron-rich Co isotopes is confirmed for mass A =72 . The new experimental information is compared to simple shell-model calculations including only neutron excitations across the f p g shells. It is shown that, in general, the calculations reproduce well the observed states.
Park, G Barratt; Jiang, Jun; Field, Robert W
2016-04-14
The C̃ (1)B2 state of SO2 has a double-minimum potential in the antisymmetric stretch coordinate, such that the minimum energy geometry has nonequivalent SO bond lengths. The asymmetry in the potential energy surface is expressed as a staggering in the energy levels of the ν3(') progression. We have recently made the first observation of low-lying levels with odd quanta of v3('), which allows us-in the current work-to characterize the origins of the level staggering. Our work demonstrates the usefulness of low-lying vibrational level structure, where the character of the wavefunctions can be relatively easily understood, to extract information about dynamically important potential energy surface crossings that occur at much higher energy. The measured staggering pattern is consistent with a vibronic coupling model for the double-minimum, which involves direct coupling to the bound 2 (1)A1 state and indirect coupling with the repulsive 3 (1)A1 state. The degree of staggering in the ν3(') levels increases with quanta of bending excitation, which is consistent with the approach along the C̃ state potential energy surface to a conical intersection with the 2 (1)A1 surface at a bond angle of ∼145°. PMID:27083727
Park, G. Barratt; Jiang, Jun; Field, Robert W.
2016-04-14
Here the C1B2 state of SO2 has a double-minimum potential in the antisymmetric stretch coordinate, such that the minimum energy geometry has nonequivalent SO bond lengths. The asymmetry in the potential energy surface is expressed as a staggering in the energy levels of the v'3 progression. We have recently made the first observation of low-lying levels with odd quanta of v'3, which allows us--in the current work--to characterize the origins of the level staggering. Our work demonstrates the usefulness of low-lying vibrational level structure, where the character of the wavefunctions can be relatively easily understood, to extract information about dynamicallymore » important potential energy surface crossings that occur at much higher energy. The measured staggering pattern is consistent with a vibronic coupling model for the double-minimum, which involves direct coupling to the bound 2 1A1 state and indirect coupling with the repulsive 3 1A1 state. The degree of staggering in the v'3 levels increases with quanta of bending excitation, which is consistent with the approach along the C state potential energy surface to a conical intersection with the 2 1A1 surface at a bond angle of ~145°.« less
NASA Astrophysics Data System (ADS)
Park, G. Barratt; Jiang, Jun; Field, Robert W.
2016-04-01
The C ˜ 1B2 state of SO2 has a double-minimum potential in the antisymmetric stretch coordinate, such that the minimum energy geometry has nonequivalent SO bond lengths. The asymmetry in the potential energy surface is expressed as a staggering in the energy levels of the ν3' progression. We have recently made the first observation of low-lying levels with odd quanta of v3', which allows us—in the current work—to characterize the origins of the level staggering. Our work demonstrates the usefulness of low-lying vibrational level structure, where the character of the wavefunctions can be relatively easily understood, to extract information about dynamically important potential energy surface crossings that occur at much higher energy. The measured staggering pattern is consistent with a vibronic coupling model for the double-minimum, which involves direct coupling to the bound 2 1A1 state and indirect coupling with the repulsive 3 1A1 state. The degree of staggering in the ν3' levels increases with quanta of bending excitation, which is consistent with the approach along the C ˜ state potential energy surface to a conical intersection with the 2 1A1 surface at a bond angle of ˜145°.
Iuchi, Satoru Koga, Nobuaki
2014-01-14
With the aim of exploring excited state dynamics, a model electronic Hamiltonian for several low-lying d−d states of [Fe(bpy){sub 3}]{sup 2+} complex [S. Iuchi, J. Chem. Phys. 136, 064519 (2012)] is refined using density-functional theory calculations of singlet, triplet, and quintet states as benchmarks. Spin−orbit coupling elements are also evaluated within the framework of the model Hamiltonian. The accuracy of the developed model Hamiltonian is determined by examining potential energies and spin−orbit couplings at surface crossing regions between different spin states. Insights into the potential energy surfaces around surface crossing regions are also provided through molecular dynamics simulations. The results demonstrate that the constructed model Hamiltonian can be used for studies on the d−d excited state dynamics of [Fe(bpy){sub 3}]{sup 2+}.
NASA Technical Reports Server (NTRS)
Goldfield, Evelyn M.; Kirby, Kate P.
1987-01-01
Configuration interaction wave functions, potential energy curves, and dipole moment functions have been calculated for the four lowest 3Sigma(-) and the three lowest 3Pi states and 5Sigma(-) states of NH. The electronic wave functions were constructed to give a balanced description of valence-Rydberg interactions. Two repulsive states have been identified as important photodissociation pathways. Spectroscopic constants are presented for the bound states, and results are compared to other theoretical and experimental work. The possible predissociation of the A 3Pi state by the 1 5Sigma(-) state is discussed.
NASA Astrophysics Data System (ADS)
Zhang, Xiaomei; Liu, Xiaoting; Liang, Guiying; Shi, Dandan; Li, Rui; Liu, Xueshen; Xu, Haifeng; Yan, Bing
2015-11-01
High-level ab initio calculations have been performed on the PBr radical by using multi-reference configuration interaction method plus Davidson correction (+Q) with correlation-consistent quadruple-ζ quality basis set. The potential energy curves (PECs) of the 22 Λ-S states of PBr have been obtained, most of which are reported for the first time. From the PECs of the bound states, the spectroscopic constants have been determined, in good agreement with the experimental results where available. Due to the large state density, there exhibits complicated interactions in the electronic excited states of PBr. The possible interactions by the spin-orbit coupling (SOC) effect have been discussed based on the evaluated R-dependent spin-orbit matrix elements. The 51 Ω states, generating from the 22 Λ-S states after taking SOC into account, have been computed. The Λ-S component analysis of the wavefunctions for the Ω states indicates the strong interaction of the Λ-S states especially at the avoided crossing points and near the dissociation limits. Finally, the transition dipole moments of several transitions arising from upper Ω states to the X10+ and X21 states and the corresponding radiative lifetimes have been studied. Our calculation results provide new information that should be valuable for further experimental studies on the electronic excited states of the PBr radical.
Xu, S.; Xie, Y.; Pan, Q.; Luo, Y.; Zhang, C.; Zhang, J.; Wang, Y.; Zhang, X.; Gu, J.; Ge, Y.; Yin, X.; Wang, C.; Xing, Z.; Chen, X.
1996-09-01
A detailed discussion and supplemental experimental information on the electron capture and {beta}{sup +} decay schemes of {sup 153}Er and {sup 157}Yb proposed in our previous publications are included. The three-quasiparticle state and single-proton states assigned to {sup 153}Ho have been reproduced by a shell model calculation. The extracted quenching factor for the three-quasiparticle state was determined to be 10. The existence of the two bands in {sup 157}Tm has been explained by a triaxial deformation of the ground state of this nucleus. The experimental evidence from systematic behavior of the compiled low-energy levels indicates that the ground-state shapes change from spherical to deformed between neutron numbers {ital N}=86 and 88 in both the odd Ho and odd Tm isotopic chains. {copyright} {ital 1996 The American Physical Society.}
NASA Astrophysics Data System (ADS)
Czekner, Joseph; Lopez, Gary V.; Wang, Lai-Sheng
2014-12-01
We report a study of the electronic and vibrational structures of the gaseous uranium monoxide and dioxide molecules using high-resolution photoelectron imaging. Vibrationally resolved photoelectron spectra are obtained for both UO- and UO2-. The spectra for UO2- are consistent with, but much better resolved than a recent study using a magnetic-bottle photoelectron analyzer [W. L. Li et al., J. Chem. Phys. 140, 094306 (2014)]. The electron affinity (EA) of UO is reported for the first time as 1.1407(7) eV, whereas a much more accurate EA is obtained for UO2 as 1.1688(6) eV. The symmetric stretching modes for the neutral and anionic ground states, and two neutral excited states for UO2 are observed, as well as the bending mode for the neutral ground state. These vibrational frequencies are consistent with previous experimental and theoretical results. The stretching vibrational modes for the ground state and one excited state are observed for UO. The current results for UO and UO2 are compared with previous theoretical calculations including relativistic effects and spin-orbit coupling. The accurate experimental data reported here provide more stringent tests for future theoretical methods for actinide-containing species.
Czekner, Joseph; Lopez, Gary V; Wang, Lai-Sheng
2014-12-28
We report a study of the electronic and vibrational structures of the gaseous uranium monoxide and dioxide molecules using high-resolution photoelectron imaging. Vibrationally resolved photoelectron spectra are obtained for both UO(-) and UO2(-). The spectra for UO2(-) are consistent with, but much better resolved than a recent study using a magnetic-bottle photoelectron analyzer [W. L. Li et al., J. Chem. Phys. 140, 094306 (2014)]. The electron affinity (EA) of UO is reported for the first time as 1.1407(7) eV, whereas a much more accurate EA is obtained for UO2 as 1.1688(6) eV. The symmetric stretching modes for the neutral and anionic ground states, and two neutral excited states for UO2 are observed, as well as the bending mode for the neutral ground state. These vibrational frequencies are consistent with previous experimental and theoretical results. The stretching vibrational modes for the ground state and one excited state are observed for UO. The current results for UO and UO2 are compared with previous theoretical calculations including relativistic effects and spin-orbit coupling. The accurate experimental data reported here provide more stringent tests for future theoretical methods for actinide-containing species. PMID:25554146
NASA Astrophysics Data System (ADS)
Arsenault, D. L.; Tokaryk, D. W.; Adam, A. G.; Linton, C.
2016-06-01
We have taken laser-induced fluorescence spectra of jet-cooled nickel monofluoride formed in a laser-ablation molecular beam source. Dispersed-fluorescence spectroscopy confirms predictions by Hougen (2011) that the parity assignments of levels in the Ω = 1 / 2 state 1570 cm-1 above the ground state should be reversed from those given in Krouti et al. (2002). The quality of the high-resolution spectra was sufficient to measure the [22.9]1.5-X1.5 band for five isotopologues of nickel and the [22.9]1.5-[0.25]0.5 band for molecules containing 58Ni and 60Ni. The spectral line positions for each isotopologue were fit to the Hamiltonian model given by Hougen, which was extended to allow for calculation of the parity-splitting parameter in the ground state.
Low-lying {sup 3}P{sup o} and {sup 3}S{sup e} states of Rb{sup -}, Cs{sup -}, and Fr{sup -}
Bahrim, C.; Thumm, U.
2000-02-01
Our Dirac R-matrix calculations suggest that none of the heavy alkali-metal negative ions, Rb, Cs, and Fr, has an excited bound state. Their lowest excited state appears to be a multiplet of {sup 3}P{sub J}{sup o}-shape resonances, the J=1 component of which was recently observed in photodetachment experiments on Cs{sup -}. We analyze these {sup 3}P{sub J}{sup o} and the {sup 3}S{sup e} excited negative ion states in partial and converged total scattering cross sections for slow electrons with incident kinetic energies below 120 meV. Our results are in excellent agreement with available experimental data. We also propose a new value for the electron affinity of Fr, provide the scattering length for electronic collisions with Rb, Cs, and Fr, and discuss the nuclear charge dependence of relativistic effects in the resonance profiles. (c) 2000 The American Physical Society.
NASA Astrophysics Data System (ADS)
DeYonker, Nathan J.; Li, Se; Yamaguchi, Yukio; Schaefer, Henry F.; Crawford, T. Daniel; King, Rollin A.; Peterson, Kirk A.
2005-06-01
The equilibrium structures and physical properties of the X˜Σ+1 linear electronic states, linear excited singlet and triplet electronic states of hydroboron monoxide (HBO) (ÃΣ-1, B˜Δ1, ãΣ+3, and b˜Δ3) and boron hydroxide (BOH) (ÃΣ+1, B˜Π1, and b˜Π3), and their bent counterparts (HBO ãA'3, b˜A″3, ÃA″1, B˜A'1 and BOH X˜A'1, b˜A'3, c˜A″3, ÃA'1, B˜A'1, C˜A″1) are investigated using excited electronic state ab initio equation-of-motion coupled-cluster (EOM-CC) methods. A new implementation of open-shell EOM-CC including iterative partial triple excitations (EOM-CC3) was tested. Coupled-cluster wave functions with single and double excitations (CCSD), single, double, and iterative partial triple excitations (CC3), and single, double, and full triple excitations (CCSDT) are employed with the correlation-consistent quadruple and quintuple zeta basis sets. The linear HBO X˜Σ+1 state is predicted to lie 48.3kcalmol-1 (2.09eV) lower in energy than the BOH X˜Σ+1 linear stationary point at the CCSDT level of theory. The CCSDT BOH barrier to linearity is predicted to lie 3.7kcalmol-1 (0.16eV). With a harmonic zero-point vibrational energy correction, the HBO X˜Σ+1-BOHX˜A'1 energy difference is 45.2kcalmol-1 (1.96eV). The lowest triplet excited electronic state of HBO, ãA'3, has a predicted excitation energy (Te) of 115kcalmol-1 (4.97eV) from the HBO ground state minimum, while the lowest-bound BOH excited electronic state, b˜A'3, has a Te of 70.2kcalmol-1 (3.04eV) with respect to BOH X˜A'1. The Te values predicted for the lowest singlet excited states are ÃA″1←X˜Σ+1=139kcalmol-1 (6.01eV) for HBO and ÃA'1←X˜A'1=102kcalmol-1 (4.42eV) for BOH. Also for BOH, the triplet vertical transition energies are b˜A'3←X˜A'1=71.4kcalmol-1 (3.10eV) and c˜A″3←X˜A'1=87.2kcalmol-1 (3.78eV).
Lică, R.; Grévy, S. [CENBG, Université de Bordeaux, CNRS Desagne, Ph. [IPHC, Université de Strasbourg, IN2P3 and others
2015-02-24
The results of the IS530 experiment at ISOLDE revealed new information concerning several nuclei close to the N ≈ 20 'Island of Inversion' - {sup 34}Mg, {sup 34}Al, {sup 34}Si. The half-life of {sup 34}Mg was found to be three times larger than the adopted value (63(1) ms instead of 20(10) ms). The beta-gamma spectroscopy of {sup 34}Mg performed for the first time in this experiment, led to the first experimental level scheme for {sup 34}Al, also showing that the full beta strength goes through the predicted 1{sup +} isomer in {sup 34}Al [1] and/or excited states that deexcite to it. The subsequent beta-decay of the 1{sup +} isomer in {sup 34}Al allowed the observation of new gamma lines in {sup 34}Si, (tentatively) associated with low-spin high-energy excited states previously unobserved.
Tran, Van Tan; Tran, Quoc Tri
2016-07-28
The geometrical and electronic structures of VSi3(-/0) clusters have been investigated with the DFT, CCSD(T), and CASSCF/CASPT2 methods. The results showed that the suitable functional to identify the ground states of VSi3(-/0) clusters is not the B3LYP but the BP86. At the BP86, CCSD(T), and CASPT2 levels, the ground state of the anionic cluster was the (1)A' ((1)A1) of tetrahedral η(3)-(Si3)V(-) isomer, while that of the neutral cluster was the 1(2)A' and 1(2)A″ (1(2)E) of the same isomer. The 1(2)A' and 1(2)A″ of the tetrahedral η(3)-(Si3)V isomer were the results of the Jahn-Teller distortions of the 1(2)E in C3v symmetry. All three bands in the photoelectron spectrum of the VSi3(-) cluster were interpreted by one-electron detachments from the (1)A' anionic ground state on the basis of the BP86, CCSD(T), and CASPT2 methods. The calculated adiabatic and vertical detachment energies were in agreement with the experimental values. The broad shape of the first band was explained by Franck-Condon factor simulations for the (1)A' → 1(2)A' and (1)A' → 1(2)A″ transitions within the tetrahedral η(3)-(Si3)V(-/0) isomers. PMID:27389039
Ab-initio calculations of low-lying excited states of water clusters (H2O)n, n = 2-6
NASA Astrophysics Data System (ADS)
Zvereva, Natalja A.; Ippolitov, Ivan I.
1997-03-01
In recent years there has been a great deal of interest in excited states of the water molecule with a number of experimental and theoretical studies reported. The umber of spectroscopic studies of complexes involving hydrogen bonding has greatly increased. However, most of this research has involved studies of the IR and Raman vibrational spectra of the molecule hydrogen bond formation strongly perturbs the vibrational transitions, but the changes in the electronic spectrum can also be observed. The interaction between water molecules is dominated by hydrogen bonding and the level of the ab initio theory is used because it accurately reproduces the major components of the interaction energy. Ab initio studies of cyclic water clusters (H2O)n, n equals 2 minus 6 and analysis of many-body interactions for ground states of these clusters has been done. The magnitudes of the two-through six-body energy terms and their contribution to the interaction energy of small ring water clusters has been computed at the Hartree-Fock (HF) and second-through fourth-order many-body perturbation (MP2, MP4) levels of theory. In this paper, we investigated the lowest S1 excited electronic states of the cyclic water clusters (H2O)n, n equals 2 minus 6 from the point of changes in the absorption spectra for many-body interactions and examined their trends as the cluster grew.
Wakabayashi, Tomonari; Wada, Yoriko; Nakajima, Kyo; Morisawa, Yusuke; Kuma, Susumu; Miyamoto, Yuki; Sasao, Noboru; Yoshimura, Motohiko; Sato, Tohru; Kawaguchi, Kentarou
2015-03-19
Laser-induced near-infrared (NIR) emission spectra of neutral bismuth timer, Bi₃, embedded in solid neon matrixes at 3 K were recorded in a range 870-1670 nm. Using photoexcitation with low energy photons at 1064 nm, two emission band systems were newly identified by their origin bands at T₀ = 6600 and 8470 cm⁻¹. Accordingly, spectral assignment for three NIR emission band systems reported recently was partly revised for the one with its origin band at T₀ = 7755 cm⁻¹ and reconfirmed for the others at T₀ = 9625 and 11,395 cm⁻¹. Energy splitting by spin-orbit coupling between the pair of electronic energy levels in the ground state of bismuth trimer, Bi₃, both having a totally symmetric vibrational mode of frequency at ω(e)" = 150 cm⁻¹, was determined to be 1870 ± 1.5 cm⁻¹. Transitions from the pair of electronically excited states, locating at T₀ = 8470 and 9625 cm⁻¹ above the ground state and separated by spin–orbit coupling of 1155 cm⁻¹, have relatively long decay constants of τ ∼0.2 and ∼0.1 ms, respectively. PMID:25357154
NASA Astrophysics Data System (ADS)
Yan, Lingling; Qu, Yizhi; Liu, Chunhua; Wang, Jianguo; Buenker, Robert J.
2012-03-01
An ab initio multireference single- and double-excitation configuration interaction (CI) study is carried out for the ground and excited electronic states of alkali-hydride cations (LiH+, NaH+, KH+, RbH+, and CsH+). For all alkali-metal atoms, the first inner-shell and valence electrons (nine active electrons, three for Li) are considered explicitly in the ab initio self-consistent-field and CI calculations. The adiabatic potential energy curves, radial and rotational couplings are calculated and presented. Short-range (˜3 a.u.) potential wells produced by the excitation of the inner-shell electrons are found. The depths of the inner potential wells are much greater than those of the outer wells for the CsH+ system. The computed spectroscopic constants for the long-range potential well of the 2 2Σ+ state are very close to the available theoretical and experimental data. The electronic states of alkali-hydrogen cations are also compared with each other, it is found that the positions of the potential wells shift to larger internuclear distances gradually, and the depths of these potential wells become greater with increasing alkali-metal atomic number. The relationships between structures of the radial coupling matrix elements and the avoiding crossings of the potential curves are analyzed. From NaH+ to CsH+, radial coupling matrix elements display more and more complex structures due to the gradual decrease of energy separations for avoided crossings. Finally, the behavior of some rotational couplings is also shown.
Erokhina, K.I.; Efimov, A.D.; Lemberg, I.K.; Mikhailov, V.M.
1985-03-01
Within the framework of the MIB-I model we have calculated energies of positive-parity levels and reduced transition probabilities between them for the /sup 70/Se, /sup 72/Se, /sup 74/Se, /sup 76/Se, /sup 78/Se, and /sup 80/Se isotopes. We conclude that states with different deformation in /sup 72//sup ,//sup 74/Se coexist and show that no stable spherical form of the /sup 76//sup ,//sup 78//sup ,//sup 80/Se nuclei exists. A relation between the MIB deformation parameters and the Bohr-Mottelson model is established.
NASA Astrophysics Data System (ADS)
Gour, Jeffrey R.; Piecuch, Piotr; Włoch, Marta
2010-10-01
The left-eigenstate completely renormalized (CR) equation-of-motion (EOM) coupled-cluster (CC) method with singles, doubles, and non-iterative triples, abbreviated as CR-EOMCC(2,3) [M. Włoch et al., Mol. Phys. 104, 2149 (2006); P. Piecuch et al., Int. J. Quantum Chem. 109, 3268 (2009)], and the companion ground-state CR-CC(2,3) methodology [P. Piecuch and M. Włoch, J. Chem. Phys. 123, 224105 (2005); P. Piecuch et al., Chem. Phys. Lett. 418, 467 (2006)] are used to determine the total electronic and adiabatic excitation energies corresponding to the ground and lowest three excited states of methylene. The emphasis is on comparing the CR-CC(2,3)/CR-EOMCC(2,3) results obtained with the large correlation-consistent basis sets of the aug-cc-pCV xZ (x = T, Q, 5) quality and the corresponding complete basis set (CBS) limits with the recently published variational and diffusion Quantum Monte Carlo (QMC) data [P. Zimmerman et al., J. Chem. Phys. 131, 124103 (2009)]. It is demonstrated that the CBS CR-CC(2,3)/CR-EOMCC(2,3) results are in very good agreement with the best QMC, i.e. diffusion MC (DMC) data, with errors in the total and adiabatic excitation energies of all calculated states on the order of a few millihartree and less than 0.1 eV, respectively, even for the challenging, strongly multi-reference C 1 A 1 state for which the basic EOMCC approach with singles and doubles completely fails. The agreement between the CBS CR-CC(2,3)/CR-EOMCC(2,3) and variational MC (VMC) results for the total energies is not as good as in the DMC case, but the excitation energies resulting from the CBS CR-CC(2,3)/CR-EOMCC(2,3) and VMC calculations agree very well.
Sorkin, Anastassia; Iron, Mark A.; Truhlar, Donald G.
2008-02-01
The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. The ground and lower excited states of Fe2, Fe2 -, and FeO+ were studied using a number of density functional theory (DFT) methods. Specific attention was paid to the relative state energies, the internuclear distances (re), and the harmonic vibrational frequencies (öe). A number of factors influencing the calculated values of these properties were examined. These include basis sets, the nature of the density functional chosen, the percentage of Hartree- Fock exchange in the density functional, and constraints on orbital symmetry. A number of different types of generalized gradient approximation (GGA) density functionals (straight GGA, hybrid GGA, meta-GGA, and hybrid meta-GGA) were examined, and it was found that the best results were obtained with hybrid GGA or hybrid meta-GGA functionals that contain nonzero fractions of HF exchange; specifically, the best overall results were obtained with B3LYP, M05, and M06, closely followed by B1LYP. One significant observation was the effect of enforcing symmetry on the orbitals. When a degenerate orbital (ð or ä) is partially occupied in the 4¼ excited state of FeO+, reducing the enforced symmetry (from C6v to C4v to C2v) results in a lower energy since these degenerate orbitals are split in the lower symmetries. The results obtained were compared to higher level ab initio results from the literature and to recent PBE+U plane wave results by Kulik et al. (Phys. Rev. Lett. 2006, 97, 103001). It was found that some of the improvements that were afforded by the semiempirical +U correction can also be accomplished by improving the form of the DFT functional and, in one case, by not enforcing high symmetry on the orbitals.
Theoretical study of spin-orbit and Coriolis coupling among the low-lying states of Rb2 and Cs2
NASA Astrophysics Data System (ADS)
Pazyuk, Elena A.; Revina, Elena I.; Stolyarov, Andrey V.
2015-11-01
The spin-orbit (SO) and angular (Coriolis) coupling matrix elements of rubidium and cesium dimers have been calculated between the states converging to the lowest three dissociation limits. The relevant quasi-relativistic matrix elements were evaluated for a wide range of internuclear distances and density grid in the basis of the spin-averaged wave functions corresponding to pure Hund's coupling case (a). Both shape and energy consistent small (9-electrons) effective core pseudopotentials were used to monitor a sensitivity of the matrix elements to the particular basis set. The dynamic correlation has been taken accounted by a large scale multi-reference configuration interaction method which was applied for only two valence electrons. The l-independent core-polarization potentials were employed to take into account the residual core-valence effect. The assessment of current accuracy of the present ab initio functions is discussed by a comparison with preceding calculations and their empirical counterparts.
Kosovich, John J.
2008-01-01
In support of U.S. Geological Survey (USGS) disaster preparedness efforts, this map depicts 1:24,000- and 1:100,000-scale quadrangle footprints over a color shaded relief representation of the State of Florida. The first 30 feet of relief above mean sea level are displayed as brightly colored 5-foot elevation bands, which highlight low-elevation areas at a coarse spatial resolution. Standard USGS National Elevation Dataset (NED) 1 arc-second (nominally 30-meter) digital elevation model (DEM) data are the basis for the map, which is designed to be used at a broad scale and for informational purposes only. The NED source data for this map consists of a mixture of 30-meter- and 10-meter-resolution DEMs. The NED data were derived from the original 1:24,000-scale USGS topographic map bare-earth contours, which were converted into gridded quadrangle-based DEM tiles at a constant post spacing (grid cell size) of either 30 meters (data before the mid-1990s) or 10 meters (mid-1990s and later data). These individual-quadrangle DEMs were then converted to spherical coordinates (latitude/longitude decimal degrees) and edge-matched to ensure seamlessness. Figure 1 shows a similar representation for the entire U.S. Gulf Coast, using coarsened 30-meter NED data. Areas below sea level typically are surrounded by levees or some other type of flood-control structures. State and county boundary, hydrography, city, and road layers were modified from USGS National Atlas data downloaded in 2003. Quadrangle names, dated April, 2006, were obtained from the Federal Geographic Names Information System. The NED data were downloaded in 2004.
NASA Astrophysics Data System (ADS)
Pazyuk, Elena A.; Revina, Elena I.; Stolyarov, Andrey V.
2016-07-01
The spin allowed electronic transition dipole moments (ETDM) of rubidium and cesium dimers are calculated among the states converging to the lowest three dissociation limits. The ETDM functions are evaluated for a wide range of internuclear distances R in the basis of the spin-averaged wavefunctions corresponding to pure Hund's coupling case (a) by using small (including the 8 subvalence +1 valence electrons) effective core pseudopotentials (ECP). The dynamic correlation is accounted for in a large scale multi-reference configuration interaction (MR-CI) method applied to only two valence electrons. The core-polarization potentials (CPP) are implemented to implicitly take the residual core-valence effect into account. The reliability of the present EDTM functions is discussed through comparison with preceding ab initio calculations and their long range perturbation theory counterparts. The achieved accuracy allowed us to quantitatively support the asymptotic behavior of the ETDM functions predicted in Marinescu and Dalgarno (1995 [4]). The long R-range transition moments could be useful to optimize stimulated Raman processes employed in ultracold molecule production.
Floquet bound states in the continuum
Longhi, Stefano; Valle, Giuseppe Della
2013-01-01
Quantum mechanics predicts that certain stationary potentials can sustain bound states with an energy buried in the continuous spectrum of scattered states, the so-called bound states in the continuum (BIC). Originally regarded as mathematical curiosities, BIC have found an increasing interest in recent years, particularly in quantum and classical transport of matter and optical waves in mesoscopic and photonic systems where the underlying potential can be judiciously tailored. Most of our knowledge of BIC is so far restricted to static potentials. Here we introduce a new kind of BIC, referred to as Floquet BIC, which corresponds to a normalizable Floquet state of a time-periodic Hamiltonian with a quasienergy embedded into the spectrum of Floquet scattered states. We discuss the appearance of Floquet BIC states in a tight-binding lattice model driven by an ac field in the proximity of the dynamic localization regime. PMID:23860625
Segado, Mireia; Gómez, Isabel; Reguero, Mar
2016-03-01
Recent theoretical and experimental studies on the Intramolecular Charge Transfer (ICT) reaction of some members of the aminobezonitrile family (ABN) suggest the involvement of a (π-σ*) excited state (called ICT(CN) in this work) in the ICT process and the existence of a partially twisted ICT species that could be responsible for the anomalous fluorescence observed. These suggestions made us to revise our previous study on the photophysics of ABN and dimethyl-ABN (DMABN), based on the analysis of the potential energy surfaces of the low-lying excited states by means of ab initio calculations, using the CASSCF/CASPT2 protocol. We have first focused our attention to ABN. We have found that the (π-σ*) excited state can be in fact an intermediary state in the path to populate the ICT bright state, although its involvement in the process is not very probable. Our results suggest that the ICT most stable species is the twisted ICT(TICT) and that the partially twisted ICT minimum found in previous studies could be an artefact of the computational method. We have also found that radiationless deactivation is a competitive reaction that must be taken into account to explain the fluorescence patterns of these systems. To confirm our theories, we have also studied other systems with a similar architecture but with a very different luminescence behaviour: dimethyl-ABN, and the 2,3,4,5-tetrafluoro derivatives of ABN and DMABN (ABN-4F and DMABN-4F). The extension of the work and the different approaches in the study of the parent system and of the derivatives make the division of the work in two parts advisable. Part I collects the characterization of the minima and reaction paths connecting the critical points of the potential energy surfaces of the states involved in the ICT reaction of ABN. We have obtained, for the first time, the pathways of radiationless deactivation for this compound. We have also computed transition energies from the excited minima, to interpret the
Spectroscopic study of low-lying {sup 16}N levels
Bardayan, D. W.; Nesaraja, C. D.; Pain, S. D.; Smith, M. S.; O'Malley, P. D.; Cizewski, J. A.; Hatarik, R.; Peters, W. A.; Blackmon, J. C.; Chae, K. Y.; Jones, K. L.; Moazen, B. H.; Paulauskas, S.; Pittman, S. T.; Schmitt, K. T.; Chipps, K. A.; Kozub, R. L.; Shriner, J. F. Jr.; Matei, C.
2008-11-15
The magnitude of the {sup 15}N(n,{gamma}){sup 16}N reaction rate in asymptotic giant branch stars depends directly on the neutron spectroscopic factors of low-lying {sup 16}N levels. A new study of the {sup 15}N(d,p){sup 16}N reaction is reported populating the ground and first three excited states in {sup 16}N. The measured spectroscopic factors are near unity as expected from shell model calculations, resolving a long-standing discrepancy with earlier measurements that had never been confirmed or understood. Updated {sup 15}N(n,{gamma}){sup 16}N reaction rates are presented.
NASA Astrophysics Data System (ADS)
Müller, Holger S. P.; Drouin, B. J.; Pearson, J. C.; Brown, L. R.; Kleiner, I.; Sams, R. L.
2010-06-01
Methyl cyanide, CH_3CN, is an important interstellar molecule, in particular in hot and dense molecular cores, and it may play a role in the atmospheres of planets or of Titan. Therefore, we have recorded extensive rotational and rovibrational spectra up to ˜ 1.6 THz and ˜ 1500 cm-1, respectively. The present investigation extends our analysis of states with v_8 ≤ 2 at vibrational energies below 740 cm-1 and takes into consideration findings from an analysis of the ν _4 band and the higher-lying ν _7 (at ˜1042 cm-1) and 3ν _8 ^1 (at ˜1078 cm-1) bands. The rotational data extend to J = 87 and K = 15, infrared assignments currently extend to 55 and 12, respectively. Parameters affecting only v_7 = 1 or v_8 = 3 as well as some additional interaction parameters were kept fixed to values from (b). The largest perturbations of v_4 = 1 are caused by a Δ k = 0, Δ l = 3 interaction with v_8 = 3 at K = 8. Despite the inclusion of the interaction parameter and a centrifugal distortion correction, residuals amount to more than 200 MHz very close to the resonance. Removal of these residuals probably requires explicit inclusion of v_8 = 3 data. Several additional perturbations exist at lower as well as higher K with v_8 = 2, v_7 = 1 and v_8 = 3. Higher values of K are difficult to reproduce in spite of an extensive set of distortion parameters which, at highest orders, have rather large magnitudes, possibly indicating unaccounted interactions which would probably occur with states even higher than v_8 = 3. H. S. P. Müller et al., contribution WG03, presented at the 62nd International Symposium on Molecular Spectroscopy, June 18-22, 2007, Columbus, Ohio, USA. A.-M. Tolonen et al., J. Mol. Spectrosc. 160 (1993) 554-565.
Low-lying isomeric levels in 75Cu
Daugas, J. M.; Faul, T.; Grawe, H.; Pfutzner, M.; Grzywacz, R.; Lewitowicz, M.; Achouri, N. L.; Bentida, R.; Beraud, R.; Borcea, C.; Bingham, C. R.; Catford, W.; Emsallem, A.; De France, G.; Grzywacz, K. L.; Lemmon, R.; Lopez Jimenez, M. J.; de Oliveira Santos, F.; Regan, P. H.; Rykaczewski, Krzysztof Piotr; Sauvestre, J. E.; Sawicka, M.; Stanoiu, M.; Sieja, K.; Nowacki, F.
2010-01-01
Isomeric low-lying states were identified and investigated in the 75Cu nucleus. Two states at 61.8(5)- and 128.3(7)-keV excitation energies with half-lives of 370(40)- and 170(15)-ns were assigned as 75m1Cu and 75m2Cu, respectively. The measured half-lives combined with the recent spin assignment of the ground state allow one to deduce tentatively spin and parity of the two isomers and the dominant multipolarities of the isomeric transitions with respect to the systematics of the Cu isotopes. Shell-model calculations using an up-to-date effective interaction reproduce the evolution of the 1/2 , 3/2 , and 5/2 states for the neutron-rich odd-mass Cu isotopes when filling the g9/2. The results indicate a significant change in the nuclear structure in this region, where a single-particle 5/2 state coexists with more and more collective 3/2 and 1/2 levels at low excitation energies.
Low-lying isomeric levels in {sup 75}Cu
Daugas, J. M.; Faul, T.; Sauvestre, J. E.; Grawe, H.; Pfuetzner, M.; Sawicka, M.; Grzywacz, R.; Lewitowicz, M.; France, G. de; Lopez Jimenez, M. J.; Oliveira Santos, F. de; Baiborodin, D.; Bentida, R.; Beraud, R.; Emsallem, A.; Bingham, C. R.; Grzywacz, K. L.
2010-03-15
Isomeric low-lying states were identified and investigated in the {sup 75}Cu nucleus. Two states at 61.8(5)- and 128.3(7)-keV excitation energies with half-lives of 370(40)- and 170(15)-ns were assigned as {sup 75m1}Cu and {sup 75m2}Cu, respectively. The measured half-lives combined with the recent spin assignment of the ground state allow one to deduce tentatively spin and parity of the two isomers and the dominant multipolarities of the isomeric transitions with respect to the systematics of the Cu isotopes. Shell-model calculations using an up-to-date effective interaction reproduce the evolution of the 1/2{sup -}, 3/2{sup -}, and 5/2{sup -} states for the neutron-rich odd-mass Cu isotopes when filling the nug{sub 9/2}. The results indicate a significant change in the nuclear structure in this region, where a single-particle 5/2{sup -} state coexists with more and more collective 3/2{sup -} and 1/2{sup -} levels at low excitation energies.
Low-lying Gamow-Teller transitions in spherical nuclei
Cakmak, N.; Uenlue, S.; Selam, C.
2012-01-15
The Pyatov Method has been used to study the low-lying Gamow-Teller transitions in the mass region of 98 Less-Than-Or-Slanted-Equal-To A Less-Than-Or-Slanted-Equal-To 130. The eigenvalues and eigenfunctions of the total Hamiltonian have been solved within the framework of proton-neutron quasiparticle random-phase approximation. The low-lying {beta} decay log(ft) values have been calculated for the nuclei under consideration.
Quantum state transfer by time reversal in the continuum
NASA Astrophysics Data System (ADS)
Longhi, S.
2016-03-01
A method for high-fidelity quantum state transfer in a quantum network coupled to a continuum, based on time reversal in the continuum after decay, is theoretically suggested. Provided that the energy spectrum of the network is symmetric around a reference energy and symmetric energy states are coupled the same way to the common continuum, ideal perfect state transfer can be obtained after time reversal. In particular, it is shown that in a linear tight-binding chain a quantum state can be transformed into its mirror image with respect to the center of the chain after a controllable time. As compared to a quantum mirror image based on coherent transport in a static chain with properly tailored inhomogeneous hopping rates, our method does not require hopping rate engineering and is less sensitive to disorder for long transfer times.
Bound states in continuum: Quantum dots in a quantum well
NASA Astrophysics Data System (ADS)
Prodanović, Nikola; Milanović, Vitomir; Ikonić, Zoran; Indjin, Dragan; Harrison, Paul
2013-11-01
We report on the existence of a bound state in the continuum (BIC) of quantum rods (QR). QRs are novel elongated InGaAs quantum dot nanostructures embedded in the shallower InGaAs quantum well. BIC appears as an excited confined dot state and energetically above the bottom of a well subband continuum. We prove that high height-to-diameter QR aspect ratio and the presence of a quantum well are indispensable conditions for accommodating the BIC. QRs are unique semiconductor nanostructures, exhibiting this mathematical curiosity predicted 83 years ago by Wigner and von Neumann.
Low-lying lattice modes of highly uniform pentacene monolayers
NASA Astrophysics Data System (ADS)
He, Rui; Tassi, Nancy G.; Blanchet, Graciela B.; Pinczuk, Aron
2009-06-01
The authors report that monolayers of pentacene grown on a functionalized polymeric substrate display high uniformity that enable observations of Raman spectra of low-lying optical vibrations. The evolution of the frequencies and widths of the modes has been studied in films reaching the single monolayer level. Raman spectra of low-lying lattice modes display major changes when the film thickness changes from 1 to 2 monolayers, revealing that a phase akin to a thin film phase of pentacene already emerges in films of only 2 monolayers.
Bound States in the Continuum in double layer structures
Li, LiangSheng; Yin, Hongcheng
2016-01-01
We have theoretically investigated the reflectivity spectrums of single- and double-layer photonic crystal slabs and the dielectric multilayer stack. It is shown that light can be perfectly confined in a single-layer photonic crystal slab at a given incident angle by changing the thickness, permittivity or hole radius of the structure. With a tunable double-layer photonic crystal slab, we demonstrate that the occurrence of tunable bound states in the continuum is dependent on the spacing between two slabs. Moreover, by analytically investigating the Drude lossless multilayer stack model, the spacing dependence of bound states in the continuum is characterized as the phase matching condition that illuminates these states can occur at any nonzero incident angles by adjusting the spacing. PMID:27245435
Bound States in the Continuum in double layer structures.
Li, LiangSheng; Yin, Hongcheng
2016-01-01
We have theoretically investigated the reflectivity spectrums of single- and double-layer photonic crystal slabs and the dielectric multilayer stack. It is shown that light can be perfectly confined in a single-layer photonic crystal slab at a given incident angle by changing the thickness, permittivity or hole radius of the structure. With a tunable double-layer photonic crystal slab, we demonstrate that the occurrence of tunable bound states in the continuum is dependent on the spacing between two slabs. Moreover, by analytically investigating the Drude lossless multilayer stack model, the spacing dependence of bound states in the continuum is characterized as the phase matching condition that illuminates these states can occur at any nonzero incident angles by adjusting the spacing. PMID:27245435
Bound States in the Continuum in double layer structures
NASA Astrophysics Data System (ADS)
Li, Liangsheng; Yin, Hongcheng
2016-06-01
We have theoretically investigated the reflectivity spectrums of single- and double-layer photonic crystal slabs and the dielectric multilayer stack. It is shown that light can be perfectly confined in a single-layer photonic crystal slab at a given incident angle by changing the thickness, permittivity or hole radius of the structure. With a tunable double-layer photonic crystal slab, we demonstrate that the occurrence of tunable bound states in the continuum is dependent on the spacing between two slabs. Moreover, by analytically investigating the Drude lossless multilayer stack model, the spacing dependence of bound states in the continuum is characterized as the phase matching condition that illuminates these states can occur at any nonzero incident angles by adjusting the spacing.
Czekner, Joseph; Lopez, Gary V.; Wang, Lai-Sheng
2014-12-28
We report a study of the electronic and vibrational structures of the gaseous uranium monoxide and dioxide molecules using high-resolution photoelectron imaging. Vibrationally resolved photoelectron spectra are obtained for both UO{sup −} and UO{sub 2}{sup −}. The spectra for UO{sub 2}{sup −} are consistent with, but much better resolved than a recent study using a magnetic-bottle photoelectron analyzer [W. L. Li et al., J. Chem. Phys. 140, 094306 (2014)]. The electron affinity (EA) of UO is reported for the first time as 1.1407(7) eV, whereas a much more accurate EA is obtained for UO{sub 2} as 1.1688(6) eV. The symmetric stretching modes for the neutral and anionic ground states, and two neutral excited states for UO{sub 2} are observed, as well as the bending mode for the neutral ground state. These vibrational frequencies are consistent with previous experimental and theoretical results. The stretching vibrational modes for the ground state and one excited state are observed for UO. The current results for UO and UO{sub 2} are compared with previous theoretical calculations including relativistic effects and spin-orbit coupling. The accurate experimental data reported here provide more stringent tests for future theoretical methods for actinide-containing species.
NASA Technical Reports Server (NTRS)
Partridge, Harry; Bauschlicher, Charles W., Jr.
1994-01-01
The potential energy curves for the manifold of molecular states dissociating to the lowest transition metal ion states derived from the 3d(sup n+1) and 3d(sup n)4s(sup 1) occupations have been determined for selected transition-metal ion- rare gas systems. These curves have been computed using large basis sets, and the state-averaged complete- active-space self-consistent-field/multireference configuration interaction level of electron correlation treatment. In general, the families of curves derived from the 3d(sup n+1) and 3d(sup n)4s(sup 1) metal occupations are disjoint; however, for Ti(+) there is a strong mixing of the 3d(sup 2)4s(sup 1) and 3d(sup 3) asymptotes, because of the small separation between the asymptotes. This mixing leads to a failure of single-reference-based techniques; this is discussed in the context of our previous single-reference-based treatments.
Low-lying structure of neutron-rich Zn and Ga isotopes
NASA Astrophysics Data System (ADS)
Jiang, H.; Fu, G. J.; Zhao, Y. M.; Arima, A.
2011-09-01
Low-lying states of even-even Zn and odd-mass Ga nuclei with neutron numbers between 42 and 50 have been calculated within the framework of the SDG-pair approximation of the nuclear shell model. We employ a monopole and quadrupole pairing plus quadrupole-quadrupole interaction with optimized parameters, which are assumed to be constants for nuclei with the same proton number or neutron number. We calculate low-lying level schemes, electric quadrupole and magnetic dipole moments, and E2 and M1 transition rates. Reasonable agreement is achieved between the calculated results and experimental data. Dominant configurations in the ground states of odd-mass Ga nuclei are discussed in terms of pair correlations. The weak-coupling picture for some states of odd-mass Ga nuclei is studied.
Andreyev, A. N.; Antalic, S.; Saro, S.; Ackermann, D.; Comas, V. F.; Heinz, S.; Heredia, J. A.; Hessberger, F. P.; Khuyagbaatar, J.; Kojouharov, I.; Kindler, B.; Lommel, B.; Mann, R.; Cocolios, T. E.; Elseviers, J.; Huyse, M.; Van Duppen, P. Van; Venhart, M.; Franchoo, S.; Hofmann, S.
2009-08-15
A detailed spectroscopic study of the neutron-deficient isotope {sup 181}Tl and the daughter of its {alpha} decay, {sup 177}Au, has been performed in the complete fusion reaction {sup 40}Ca+{sup 144}Sm{yields}{sup 184}Pb* at the velocity filter SHIP (GSI). The mass excess, excitation energy, and decay scheme of the isomeric 1.40(3) ms, 9/2{sup -} intruder state in {sup 181}Tl have been established for the first time. These results solve a long-standing puzzle of the unrealistically large reduced {alpha}-decay width of this isomer. Based on this, the previously unknown masses of the long-lived isomeric states in {sup 177}Au and {sup 173}Ir have been derived. In turn, it now allows the excitation energies of previously identified bands in {sup 177}Au and {sup 173}Ir to be deduced and compared with theoretical predictions. First measurements of {alpha}-decay branching ratios for {sup 181}Tl{sup m} and {sup 177}Au{sup m,g} are also reported.
Analytic continuation as a bridge between continuum and bound states
NASA Astrophysics Data System (ADS)
Blokhintsev, Leonid; Savin, Dmitry
2015-05-01
The problem of obtaining characteristics of bound nuclear states from continuum states data is discussed. It is shown that the ambiguities due to the existence of phase-equivalent potentials can be resolved by using the analytic properties of scattering amplitudes. The methods of determination of asymptotic normalization coefficients and vertex constants are considered. The asymptotic normalization coefficients for 6Li in the α + d channel are found by analytic continuation of the two-channel effective range expansion. The account of inelastic channels within the effective range approach is discussed.
Mechanical bound state in the continuum for optomechanical microresonators
NASA Astrophysics Data System (ADS)
Chen, Yuan; Shen, Zhen; Xiong, Xiao; Dong, Chun-Hua; Zou, Chang-Ling; Guo, Guang-Can
2016-06-01
Clamping loss limits the quality factor of mechanical mode in the optomechanical resonators supported with the supporting stem. Using the mechanical bound state in the continuum (BIC), we have found that the mechanical clamping loss can be avoided. The mechanical quality factor of a microsphere could be achieved up to 108 for a specific radius of the stem, which forms a mechanical BIC with the combination of the symmetry protected mechanism and the single resonance mechanism. Such a mechanism is proved to be universal for different geometries and materials, thus can also be generalized to design high quality mechanical resonators.
Block versus continuum deformation in the Western United States
King, G.; Oppenheimer, D.; Amelung, F.
1994-01-01
The relative role of block versus continuum deformation of continental lithosphere is a current subject of debate. Continuous deformation is suggested by distributed seismicity at continental plate margins and by cumulative seismic moment sums which yield slip estimates that are less than estimates from plate motion studies. In contrast, block models are favored by geologic studies of displacement in places like Asia. A problem in this debate is a lack of data from which unequivocal conclusions may be reached. In this paper we apply the techniques of study used in regions such as the Alpine-Himalayan belt to an area with a wealth of instrumental data-the Western United States. By comparing plate rates to seismic moment release rates and assuming a typical seismogenic layer thickness of 15 km it appears that since 1850 about 60% of the Pacific-North America motion across the plate boundary in California and Nevada has occurred seismically and 40% aseismically. The San Francisco Bay area shows similar partitioning between seismic and aseismic deformation, and it can be shown that within the seismogenic depth range aseismic deformation is concentrated near the surface and at depth. In some cases this deformation can be located on creeping surface faults, but elsewhere it is spread over a several kilometer wide zone adjacent to the fault. These superficial creeping deformation zones may be responsible for the palaeomagnetic rotations that have been ascribed elsewhere to the surface expression of continuum deformation in the lithosphere. Our results support the dominant role of non-continuum deformation processes with the implication that deformation localization by strain softening must occur in the lower crust and probably the upper mantle. Our conclusions apply only to the regions where the data are good, and even within the Western United States (i.e., the Basin and Range) deformation styles remain poorly resolved. Nonetheless, we maintain that block motion is the
Low-lying Level Structure of 150Nd
NASA Astrophysics Data System (ADS)
Chakraborty, A.; Prados-Estévez, F. M.; Yates, S. W.; Choudry, S. N.; Crider, B. P.; Kumar, A.; McEllistrem, M. T.; Mukhopadhyay, S.; Orce, J. N.; Mynk, M. G.; Peters, E. E.; Garrett, P. E.; Kulp, W. D.; Wood, J. L.
2011-10-01
To address the issue of whether the 150Nd nucleus represents an example of a phase transition in the shape degree of freedom or a complex example of shape coexistence, its level structure, up to about 2 MeV excitation and 6 ℏ, has been explored via the (n ,n' γ) reaction at the University of Kentucky accelerator facility. Level lifetimes, in the sub-picosecond regime, were extracted with a Doppler-shift attenuation analysis. A significant extension of the level scheme was possible, and the observed low-lying level structure of 150Nd indicates a close resemblance to its neighboring 152Sm isotone. Results from the ongoing analysis will be presented. This material is based on work supported by the U.S. National Science Foundation under Grant No. PHY-0956310.
Low-Lying Structure of 132,134Xe from Inelastic Neutron Scattering
NASA Astrophysics Data System (ADS)
Peters, E. E.; Chakraborty, A.; Crider, B. P.; Kumar, A.; Prados-Estèvez, F. M.; Ashley, S. F.; Elhami, E.; Mukhopadhyay, S.; Orce, J. N.; McEllistrem, M. T.; Yates, S. W.
2013-03-01
The low-lying structure of 132Xe and 134Xe has been studied using the (n, n' γ) reaction at the University of Kentucky 7-MV Van de Graaff accelerator facility. Gamma-ray excitation function and angular distribution measurements were performed. Lifetimes were measured using the Doppler-shift attenuation method, and transition probabilities were obtained. Previous assignments of mixed-symmetry states in each nucleus are supported. Also, a tentative Jπ = 0+ state is supported for 134Xe, and a new one is proposed for 134Xe.
Microscopic study of low-lying collective bands in 77 Kr
NASA Astrophysics Data System (ADS)
Tripathy, K. C.; Sahu, R.; Mishra, S.
2006-02-01
The structure of the collective bands in ^{77}Kr is investigated within our deformed shell model (DSM) based on Hartree-Fock states. The different levels are classified into collective bands on the basis of their B(E2) values. The calculated K= 5/2^+ ground band agrees reasonably well with the experiment. An attempt has been made to study the structure of the 3-quasiparticle band based on large J state in this nucleus. The calculated collective bands, the B(E2), and B(M1) values are compared with available experimental data. The nature of alignments in the low-lying bands is also analyzed.
Origin of low-lying enhanced E1 strength in rare-Earth nuclei.
Spieker, M; Pascu, S; Zilges, A; Iachello, F
2015-05-15
The experimental E1 strength distribution below 4 MeV in rare-earth nuclei suggests a local breaking of isospin symmetry. In addition to the octupole states, additional J^{π}=1^{-} states with enhanced E1 strength have been observed in rare-earth nuclei by means of (γ,γ') experiments. By reproducing the experimental results, the spdf interacting boson model calculations provide further evidence for the formation of an α cluster in medium-mass nuclei and might provide a new understanding of the origin of low-lying E1 strength. PMID:26024168
Bound states at exceptional points in the continuum
NASA Astrophysics Data System (ADS)
Fernández-García, N.; Hernández, E.; Jáuregui, A.; Mondragón, A.
2014-05-01
In this work, an example of exceptional points in the continuous spectrum of a Hamiltonian of von Neumann-Wigner type is presented and discussed. Remarkably, these exceptional points are not associated with a double pole in the scattering matrix but with a double pole in the normalization factor of the Jost eigenfunctions normalized to unit flux. At the exceptional points the two unnormalized Jost eigenfunctions are no longer linearly independent but coalesce to give rise to two Jordan cycles of generalized bound state energy eigenfunctions in the continuum and a Jordan block representation of the Hamiltonian. The regular scattering eigenfunction vanishes at the exceptional points and the irregular scattering eigenfunction has a double pole at the exceptional points. The scattering matrix is a regular analytical function of the wave number k for all k real including the exceptional points.
Low-lying {Lambda} baryons with spin 1/2 in two-flavor lattice QCD
Takahashi, Toru T.; Oka, Makoto
2010-02-01
Low-lying {Lambda} baryons with spin 1/2 are analyzed in full (unquenched) lattice QCD. We construct 2x2 cross correlators from flavor SU(3) octet and singlet baryon operators, and diagonalize them so as to extract information of two low-lying states for each parity. The two-flavor CP-PACS gauge configurations are used, which are generated in the renormalization-group improved gauge action and the O(a)-improved quark action. Three different {beta}'s, {beta}=1.80, 1.95, and 2.10, are employed, whose corresponding lattice spacings are a=0.2150, 0.1555, and 0.1076 fm. For each cutoff, we use four hopping parameters, ({kappa}{sub val},{kappa}{sub sea}), which correspond to the pion masses ranging about from 500 MeV to 1.1 GeV. Results indicate that there are two negative-parity {Lambda} states nearly degenerate at around 1.6 GeV, while no state as low as {Lambda}(1405) is observed. By decomposing the flavor components of each state, we find that the lowest (1st-excited) negative-parity state is dominated by flavor-singlet (flavor-octet) component. We also discuss meson-baryon components of each state, which has drawn considerable attention in the context of multiquark pictures of {Lambda}(1405).
Continuum-state and bound-state β--decay rates of the neutron
NASA Astrophysics Data System (ADS)
Faber, M.; Ivanov, A. N.; Ivanova, V. A.; Marton, J.; Pitschmann, M.; Serebrov, A. P.; Troitskaya, N. I.; Wellenzohn, M.
2009-09-01
For the β--decay of the neutron we analyze the continuum-state and bound-state decay modes. We calculate the decay rates, the electron energy spectrum for the continuum-state decay mode, and angular distributions of the decay probabilities for the continuum-state and bound-state decay modes. The theoretical results are obtained for the new value for the axial coupling constant gA=1.2750(9), obtained recently by H. Abele [Prog. Part. Nucl. Phys. 60, 1 (2008)] from the fit of the experimental data on the coefficient of the correlation of the neutron spin and the electron momentum of the electron energy spectrum of the continuum-state decay mode. We take into account the contribution of radiative corrections and the scalar and tensor weak couplings. The calculated angular distributions of the probabilities of the bound-state decay modes of the polarized neutron can be used for the experimental measurements of the bound-state β--decays into the hyperfine states with total angular momentum F=1 and scalar and tensor weak coupling constants.
Proton capture to continuum states of {sup 209}Bi
Likar, A.; Lipoglavsek, M.; Vencelj, M.; Vidmar, T.; Bark, R.A.; Gueorguieva, E.; Komati, F.; Lawrie, J.J.; Maliage, S.M.; Mullins, S.M.; Murray, S.H.T.; Ramashidzha, T.M.
2006-04-15
High resolution spectra from fast proton radiative capture in {sup 208}Pb are presented for three energies of the incident protons: 14.8, 15.7, and 16.9 MeV. The collected spectra were analyzed with emphasis on the region of capture to unbound states in order to search for possible structure and to study the competition between two basically different phenomena: the statistical process versus the fluctuation effects in radiative capture to unbound final states. In the energy region of incoming protons considered in our experiment, the statistical processes modeled with a Hauser-Feshbach calculation dominate. The spectra of primary {gamma} rays, coincident with the low energy one from the decay of the f{sub 7/2} single-particle state, show a prominent structure which is predominantly of g{sub 9/2} character. The calculations of continuum spectra based on the extended direct-semidirect model and the Hauser-Feshbach statistical approach successfully reproduce the experimental data.
Low-lying excitations in a strongly interacting Fermi gas
NASA Astrophysics Data System (ADS)
Vale, Christopher; Hoinka, Sascha; Dyke, Paul; Lingham, Marcus
2016-05-01
We present measurements of the low-lying excitation spectrum of a strongly interacting Fermi gas across the Bardeen-Cooper-Schrieffer (BCS) to Bose-Einstein condensate (BEC) crossover using Bragg spectroscopy. By focussing the Bragg lasers onto the central volume of the cloud we can probe atoms at near-uniform density allowing measurement of the homogeneous density-density response function. The Bragg wavevector is set to be approximately half of the Fermi wavevector to probe the collective response. Below the superfluid transition temperature the Bragg spectra dominated by the Bogoliubov-Anderson phonon mode. Single particle excitations become visible at energies greater than twice the pairing gap. As interactions are tuned from the BCS to BEC regime the phonon and single particle modes separate apart and both the pairing gap and speed of sound can be directly read off in certain regions of the crossover. Single particle pair-breaking excitations become heavily suppressed as interactions are tuned from the BCS to BEC regimes.
Low-Lying Structure of 50Ar and the N =32 Subshell Closure
NASA Astrophysics Data System (ADS)
Steppenbeck, D.; Takeuchi, S.; Aoi, N.; Doornenbal, P.; Matsushita, M.; Wang, H.; Utsuno, Y.; Baba, H.; Go, S.; Lee, J.; Matsui, K.; Michimasa, S.; Motobayashi, T.; Nishimura, D.; Otsuka, T.; Sakurai, H.; Shiga, Y.; Shimizu, N.; Söderström, P.-A.; Sumikama, T.; Taniuchi, R.; Valiente-Dobón, J. J.; Yoneda, K.
2015-06-01
The low-lying structure of the neutron-rich nucleus 50Ar has been investigated at the Radioactive Isotope Beam Factory using in-beam γ -ray spectroscopy with 9Be (54Ca, 50Ar +γ )X , 9Be (55Sc, 50Ar +γ )X , and 9Be (56Ti, 50Ar +γ )X multinucleon removal reactions at ˜220 MeV /u . A γ -ray peak at 1178(18) keV is reported and assigned as the transition from the first 2+ state to the 0+ ground state. A weaker, tentative line at 1582(38) keV is suggested as the 41+→21+ transition. The experimental results are compared to large-scale shell-model calculations performed in the s d p f model space using the SDPF-MU effective interaction with modifications based on recent experimental data for exotic calcium and potassium isotopes. The modified Hamiltonian provides a satisfactory description of the new experimental results for 50Ar and, more generally, reproduces the energy systematics of low-lying states in neutron-rich Ar isotopes rather well. The shell-model calculations indicate that the N =32 subshell gap in 50Ar is similar in magnitude to those in 52Ca and 54Ti and, notably, predict an N =34 subshell closure in 52Ar that is larger than the one recently reported in 54Ca.
Strain-Induced Localized States Within the Matrix Continuum of Self-Assembled Quantum Dots
Popescu, V.; Bester, G.; Zunger, A.
2009-07-01
Quantum dot-based infrared detectors often involve transitions from confined states of the dot to states above the minimum of the conduction band continuum of the matrix. We discuss the existence of two types of resonant states within this continuum in self-assembled dots: (i) virtual bound states, which characterize square wells even without strain and (ii) strain-induced localized states. The latter emerge due to the appearance of 'potential wings' near the dot, related to the curvature of the dots. While states (i) do couple to the continuum, states (ii) are sheltered by the wings, giving rise to sharp absorption peaks.
Semirelativistic potential model for low-lying three-gluon glueballs
Mathieu, Vincent; Semay, Claude; Silvestre-Brac, Bernard
2006-09-01
The three-gluon glueball states are studied with the generalization of a semirelativistic potential model giving good results for two-gluon glueballs. The Hamiltonian depends only on 3 parameters fixed on two-gluon glueball spectra: the strong coupling constant, the string tension, and a gluon size which removes singularities in the potential. The Casimir scaling determines the structure of the confinement. Low-lying J{sup PC} states are computed and compared with recent lattice calculations. A good agreement is found for 1{sup --} and 3{sup --} states, but our model predicts a 2{sup --} state much higher in energy than the lattice result. The 0{sup -+} mass is also computed.
Low-lying isovector 2+ valence-shell excitations of 212Po
NASA Astrophysics Data System (ADS)
Kocheva, D.; Rainovski, G.; Jolie, J.; Pietralla, N.; Stahl, C.; Petkov, P.; Blazhev, A.; Hennig, A.; Astier, A.; Braunroth, Th.; Cortés, M. L.; Dewald, A.; Djongolov, M.; Fransen, C.; Gladnishki, K.; Karayonchev, V.; Litzinger, J.; Müller-Gatermann, C.; Scheck, M.; Scholz, Ph.; Stegmann, R.; Thöle, P.; Werner, V.; Witt, W.; Wölk, D.; Van Isacker, P.
2016-01-01
We present the results from an experiment dedicated to search for quadrupole-collective isovector valence-shell excitations, states with so-called mixed proton-neutron symmetry (MSS), of 212Po. This nucleus was studied in an α -transfer reaction. The lifetimes of two short-lived excited states, candidates for the one-phonon MSS, were determined by utilizing the Doppler shift attenuation method. The experimental results are in qualitative agreement with a simple single-j shell model calculation, which, together with the observed lack of quadrupole collectivity, indicates that the isovector nature of low-lying states is a property of the leading single-particle valence shell configuration.
Construction of a state evolution for Kawasaki dynamics in continuum
NASA Astrophysics Data System (ADS)
Berns, Christoph; Kondratiev, Yuri; Kutoviy, Oleksandr
2013-06-01
We consider conservative, non-equilibrium stochastic jump dynamics of interacting particles in continuum. These dynamics have a (grand canonical) Gibbs measure as invariant measure. The problem of existence of these dynamics is studied. The corresponding time evolution of correlation functions is constructed.
Bound-state eigenenergy outside and inside the continuum for unstable multilevel systems
NASA Astrophysics Data System (ADS)
Miyamoto, Manabu
2005-12-01
The eigenvalue problem for the dressed bound state of unstable multilevel systems is examined both outside and inside the continuum, based on the N -level Friedrichs model, which describes the couplings between the discrete levels and the continuous spectrum. It is shown that a bound-state eigenenergy always exists below each of the discrete levels that lie outside the continuum. Furthermore, by strengthening the couplings gradually, the eigenenergy corresponding to each of the discrete levels inside the continuum finally emerges. On the other hand, the absence of the eigenenergy inside the continuum is proved in weak but finite coupling regimes, provided that each of the form factors that determine the transition between some definite level and the continuum does not vanish at that energy level. An application to the spontaneous emission process for the hydrogen atom interacting with the electromagnetic field is demonstrated.
Low-lying hypernuclei in the relativistic quark-gluon model
NASA Astrophysics Data System (ADS)
Gerasyuta, S. M.; Matskevich, E. E.
2013-06-01
Low-lying hypernuclei HΛ3, Σ30H, HeΛ3, Σ30He are described by the relativistic nine-quark equations in the framework of the dispersion relation technique. The approximate solutions of these equations are obtained using a method based on the extraction of leading singularities of the amplitudes. The relativistic nine-quark amplitudes of hypernuclei, including the quarks of three flavors (u,d,s), are calculated. The poles of these amplitudes determine the masses of hypernuclei. The mass of state HΛ3 with the isospin projection I3=0 and the spin-parity JP=(1)/(2)(+)/() is equal to M=2991MeV.
Continuum limit of lattice models with Laughlin-like ground states containing quasiholes
NASA Astrophysics Data System (ADS)
Rodríguez, Iván D.; Nielsen, Anne E. B.
2015-09-01
There has been significant interest in recent years in finding fractional quantum Hall physics in lattice models, but it is not always clear how these models connect to the corresponding models in continuum systems. Here we introduce a family of models that is able to interpolate between a recently proposed set of lattice models with Laughlin-like ground states constructed from conformal field theory and models with ground states that are practically the usual bosonic/fermionic Laughlin states in the continuum. Both the ground state and the Hamiltonian are known analytically, and we find that the Hamiltonian in the continuum limit does not coincide with the usual delta interaction Hamiltonian for the Laughlin states. We introduce quasiholes into the models and show analytically that their braiding properties are as expected if the quasiholes are screened. We demonstrate screening numerically for the 1/3 Laughlin model and find that the quasiholes are slightly smaller in the continuum than in the lattice. Finally, we compute the effective magnetic field felt by the quasiholes and show that it is close to uniform when approaching the continuum limit. The techniques presented here to interpolate between the lattice and the continuum can also be applied to other fractional quantum Hall states that are constructed from conformal field theory.
Low-lying levels in /sup 148/Pm
Norman, E.B.; Lesko, K.T.; Champagne, A.E.
1988-02-01
The /sup 149/Sm(d,/sup 3/He) reaction has been used to populate levels in /sup 148/Pm. Nineteen new excited states have been observed below 1 MeV excitation energy in /sup 148/Pm. The possible astrophysical implications of these results are discussed.
Low-lying dipole strength of the open-shell nucleus 94Mo
NASA Astrophysics Data System (ADS)
Romig, C.; Beller, J.; Glorius, J.; Isaak, J.; Kelley, J. H.; Kwan, E.; Pietralla, N.; Ponomarev, V. Yu.; Sauerwein, A.; Savran, D.; Scheck, M.; Schnorrenberger, L.; Sonnabend, K.; Tonchev, A. P.; Tornow, W.; Weller, H. R.; Zilges, A.; Zweidinger, M.
2013-10-01
The low-lying dipole strength of the open-shell nucleus 94Mo was studied via the nuclear resonance fluorescence technique up to 8.7 MeV excitation energy at the bremsstrahlung facility at the Superconducting Darmstadt Electron Linear Accelerator (S-DALINAC), and with Compton backscattered photons at the High Intensity γ-ray Source (HIγS) facility. In total, 83 excited states were identified. Exploiting polarized quasi-monoenergetic photons at HIγS, parity quantum numbers were assigned to 41 states excited by dipole transitions. The electric dipole-strength distribution was determined up to 8.7 MeV and compared to microscopic calculations within the quasiparticle phonon model. Calculations and experimental data are in good agreement for the fragmentation, as well as for the integrated strength. The average decay pattern of the excited states was investigated exploiting the HIγS measurements at five energy settings. Mean branching ratios to the ground state and first excited 21+ state were extracted from the measurements with quasi-monoenergetic photons and compared to γ-cascade simulations within the statistical model. The experimentally deduced mean branching ratios exhibit a resonance-like maximum at 6.4 MeV which cannot be reproduced within the statistical model. This indicates a nonstatistical structure in the energy range between 5.5 and 7.5 MeV.
Anharmonic Resonances among Low-Lying Vibrational Levels of Methyl Iso-Cyanide (H_3CNC)
NASA Astrophysics Data System (ADS)
Pracna, P.; Urban, J.; Urban, V. S.; Varga, J.; Horneman, V.-M.
2010-06-01
Vibrational levels up to 1000 wn of H_3C-N≡C are currently studied in FTIR spectra together with rotational transitions within these levels. This investigation comprises the low-lying excited vibrational levels of the CNC doubly degenerate bending vibration v8=1^± 1 (267.3 wn), v8=20,± 2 (524.6 wn (A), 545.3 wn (E)), and v8=3^± 1,± 3 (792.5 wn (A1+A2), 833.9 wn (E)), respectively, and the next higher fundamental level of the C-N valence vibration v4=1 (945 wn). All these vibrational levels exhibit cubic and quartic anharmonic resonances localized to moderate values of the rotational quantum number K≤10. Therefore the system of rovibrational levels has to be treated as a global polyad in order to describe all the available data quantitatively. The ground state constants have been improved considerably by extending the assignments to higher J/K rotational states both in the purely rotational spectra recorded in the ground vibrational level and in the ground state combination differences generated from the wavenumbers assigned in the fundamental ν_4 band. Similarities and differences with respect to isoelectronic molecules CH_3CN and CH_3CCH are discussed.
Testing the tetraquark structure for the X resonances in the low-lying region
NASA Astrophysics Data System (ADS)
Kim, Hungchong; Kim, K. S.; Cheoun, Myung-Ki; Jido, Daisuke; Oka, Makoto
2016-07-01
Assuming the four-quark structure for the X resonances in the low-lying region, we calculate their masses using the color-spin interaction. Specifically, the hyperfine masses of the color-spin interaction are calculated for the possible states in spin-0, spin-1, spin-2 channels. The two states in spin-0 channel as well as the two states in spin-1 channel are diagonalized in order to generate the physical hyperfine masses. By matching the difference in hyperfine masses with the splitting in corresponding hadron masses and using the X(3872) mass as an input, we estimate the masses corresponding to the states J^{PC}=0^{++} , 1^{+-} , 2^{++} . We find that the masses of two states in 1^{+-} are close to those of X(3823) , X(3900) , and the mass of the 2^{++} state is close to that of X(3940) . For them, the discrepancies are about ˜ 10 MeV. This may suggest that the quantum numbers of the controversial states are X(3823)=1^{+-} , X(3900)=1^{+-} , X(3940)=2^{++} . In this work, we use the same inputs parameters, the constituent quark masses and the strength of the color-spin interaction, that have been adopted in the previous work on the D - or B -meson excited states. There, it was shown that the four-quark structure can be manifested in their excited states. Thus, our results in this work provide a consistent treatment on open- and hidden-charm mesons as far as the four-quark model is concerned.
Searching for low-lying multi-particle thresholds in lattice spectroscopy
Mahbub, M. Selim; Kamleh, Waseem; Leinweber, Derek B.; Williams, Anthony G.
2014-03-15
We explore the Euclidean-time tails of odd-parity nucleon correlation functions in a search for the S-wave pion–nucleon scattering-state threshold contribution. The analysis is performed using 2+1 flavor 32{sup 3}×64 PACS-CS gauge configurations available via the ILDG. Correlation matrices composed with various levels of fermion source/sink smearing are used to project low-lying states. The consideration of 25,600 fermion propagators reveals the presence of more than one state in what would normally be regarded as an eigenstate-projected correlation function. This observation is in accord with the scenario where the eigenstates contain a strong mixing of single and multi-particle states but only the single particle component has a strong coupling to the interpolating field. Employing a two-exponential fit to the eigenvector-projected correlation function, we are able to confirm the presence of two eigenstates. The lower-lying eigenstate is consistent with a Nπ scattering threshold and has a relatively small coupling to the three-quark interpolating field. We discuss the impact of this small scattering-state contamination in the eigenvector projected correlation function on previous results presented in the literature. -- Highlights: • Correlation-matrix projected correlators reveal more than one state contributing. • Results are associated with strong mixing of single and multi-particle states in QCD. • A two-exponential fit confirms the presence of two QCD eigenstates. •The lower-lying eigenstate is consistent with a nucleon–pion scattering threshold. •The impact of this small contamination on the higher-lying state is examined.
Low-lying stepwise paths for ethylene 1,3-dipolar cycloadditions: A DFT study
NASA Astrophysics Data System (ADS)
Kavitha, K.; Venuvanalingam, P.
Ethylene reacts with 1,3-dipoles such as diazomethane, nitrile oxide, and nitrone to give a single adduct and the potential energy surfaces of these reactions were completely surveyed with Density Functional Theory at the B3LYP/6-31G(d) level; B3LYP/6-311+G(d,p), QCISD/6-31G(d) level calculations were performed for comparison. These reactions were found to have one concerted and four stepwise paths and all of them were thoroughly examined. Calculations show that anti and syn approaches in the stepwise paths merge at one point in the potential energy surface and the stepwise processes (i.e., through syn transition states) are low-lying and concerted paths that are in close competition with them. A closer examination of the computed barriers of the reactions of ethylene with the above dipoles, cyclopentadiene, 1,3-butadiene, and allyl anion reveals that there is a mechanistic cross-over from concerted to stepwise path. While the neutral cycloaddition partners prefer a concerted path, the charged partners strongly favor a stepwise path. The dipoles have both concerted and stepwise (syn) paths in close competition. Such a mechanistic cross-over has been induced by the polar influence of the charged species and this change-over in mechanism could not be observed with allene cycloadditions with the same set of partners because allene is strongly biased towards the stepwise mechanism.
Experimental study of the low-lying structure of {sup 94}Zr with the (n,n{sup '}{gamma}) reaction
Elhami, E.; Orce, J. N.; Scheck, M.; Mukhopadhyay, S.; Choudry, S. N.; McEllistrem, M. T.; Yates, S. W.; Angell, C.; Boswell, M.; Karwowski, H. J.; Fallin, B.; Howell, C. R.; Hutcheson, A.; Parpottas, Y.; Tonchev, A. P.; Tornow, W.; Kelley, J. H.
2008-12-15
The low-lying structure of {sub 40}{sup 94}Zr was studied with the (n,n{sup '}{gamma}) reaction, and a level scheme was established based on excitation function and {gamma}{gamma} coincidence measurements. Branching ratios, multipole mixing ratios, and spin assignments were determined from angular distribution measurements. Lifetimes of levels up to 3.4 MeV were measured by the Doppler-shift attenuation method, and for many transitions the reduced transition probabilities were determined. In addition to the anomalous 2{sub 2}{sup +} state, which has a larger B(E2;2{sub 2}{sup +}{yields}0{sub 1}{sup +}) value than the B(E2;2{sub 1}{sup +}{yields}0{sub 1}{sup +}), the experimental results revealed interesting and unusual properties of the low-lying states in {sup 94}Zr. In a simple interpretation, the excited states are classified in two distinct categories, i.e., those populating the 2{sub 2}{sup +} state and those decaying to the 2{sub 1}{sup +} state.
Energies and Electric Dipole Transitions for Low-Lying Levels of Protactinium IV and Uranium V
NASA Astrophysics Data System (ADS)
Ürer, Güldem; Özdemir, Leyla
2012-02-01
We have reported a relativistic multiconfiguration Dirac-Fock (MCDF) study on low-lying level structures of protactinium IV (Z =91) and uranium V (Z =92) ions. Excitation energies and electric dipole (E1) transition parameters (wavelengths, oscillator strengths, and transition rates) for these low-lying levels have been given. We have also investigated the influence of the transverse Breit and quantum electrodynamic (QED) contributions besides correlation effects on the level structure. A comparison has been made with a few available data for these ions in the literature.
Low-lying levels of 76Ge, a candidate for neutrinoless double- β decay
NASA Astrophysics Data System (ADS)
Mukhopadhyay, S.; B. P. Crider Team; E. E. Peters Team; F. M. Prados-Este'vez Team; M. T. McEllistrem Team; S. W. Yates Team
2015-10-01
The low-spin structure of 76Ge was studied at the University of Kentucky with the (n,n' γ) reaction. This nucleus is a parent in double- β decay and is also a rare example of a nucleus to exhibit rigid triaxial deformation in the low-lying states. Excitation function measurements performed with neutrons from 1.6 to 3.7 MeV helped determine the threshold for the γ rays and hence their placement in the level scheme. Lifetimes, spins,multipolarities, and branching ratios were obtained from angular distributions measured at neutron energies of 3.0 and 3.5 MeV. New levels identified around 2 MeV will give insight to the nuclear structure aspects of 76Ge. It is also important to identify any γ rays around 2039 keV, as the experimental signature for neutrinoless double- β decay is a weak peak at this energy. In a recent study with 4.9-MeV neutrons, a reported 2039-keV γ ray from the 3952-keV level was not observed. However, definitely a new level at 3147 keV with 2584- and 2038-keV γ rays to the 21+ and 22+ states, respectively was established. These findings indicate that backgrounds in the search for the neutrinoless double- β decay of 76Ge may be more complex. This material is based upon work supported by the U.S. National Science Foundation under Grant No. PHY-1305801.
Evaluating the 100 year floodplain as an indicator of flood risk in low-lying coastal watersheds
NASA Astrophysics Data System (ADS)
Sebastian, A.; Brody, S.; Bedient, P. B.
2013-12-01
The Gulf of Mexico is the fastest growing region in the United States. Since 1960, the number of housing units built in the low-lying coastal counties has increased by 246%. The region experiences some of the most intense rainfall events in the country and coastal watersheds are prone to severe flooding characterized by wide floodplains and ponding. This flooding is further exacerbated as urban development encroaches on existing streams and waterways. While the 100 year floodplain should play an important role in our ability to develop disaster resilient communities, recent research has indicated that existing floodplain delineations are a poor indicator of actual flood losses in low-lying coastal regions. Between 2001 and 2005, more than 30% of insurance claims made to FEMA in the Gulf Coast region were outside of the 100 year floodplain and residential losses amounted to more than $19.3 billion. As population density and investments in this region continue to increase, addressing flood risk in coastal communities should become a priority for engineers, urban planners, and decision makers. This study compares the effectiveness of 1-D and a 2-D modeling approaches to spatially capture flood claims from historical events. Initial results indicate that 2-D models perform much better in coastal environments and may serve better for floodplain modeling helping to prevent unintended losses. The results of this study encourage a shift towards better engineering practices using existing 2-D models in order to protect resources and provide guidance for urban development in low-lying coastal regions.
Low-lying spectra of {sup 9}{Lambda}Be and {sup 9}Be within three-cluster model
Filikhin, I.; Suslov, V. M.; Vlahovic, B.
2011-10-24
An {alpha}-cluster model is applied to study the low-lying spectra of the {sup 9}{Lambda}Be and {sup 9}Be nuclei. The {alpha}{alpha}{Lambda} and {alpha}{alpha}n three-body problems are numerically solved by the Faddeev equations in configuration space using phenomenological pair potentials with spin-orbital {alpha}{Lambda} and {alpha}n interactions taken into account. For the {sup 9}{Lambda}Be hypernucleus we found a set of the potentials that reproduces the experimental data for the ground state (1/2 {sup +}) binding energy and excitation energy of the 5/2{sup +} and 3/2 {sup +} states, simultaneously. The LS coupling scheme is used for partial wave analysis. The total orbital momentum is fixed for each energy level. Under this assumption we calculated the {sup 9}Be spectrum within {alpha}{alpha}n model. The experiential data are well reproduced by the model, when a new classification for low-lying levels of {sup 9}Be as members of spin-flip doublets is applied.
NASA Astrophysics Data System (ADS)
Margolis, Jack S.; Liu, Karen Y.; Moynihan, Philip I.
1999-01-01
The sensitivity of spectroscopic detection of low-lying gas clouds by an arbitrary spectrometer may be determined by simulating the observation using a high spectral resolution radiative transfer code. The instrumental characteristics may be superimposed on the simulation and the accuracy of the retrieval of the desired parameters may be estimated by use of the covariance matrix.
NASA Astrophysics Data System (ADS)
Gao, Xiang; Jin, Rui; Zeng, De-Ling; Han, Xiao-Ying; Yan, Jun; Li, Jia-Ming
2015-11-01
The electron and photon scattering data of an atom are crucial for many scientific fields, including plasma physics, astrophysics, and so on. For high enough but nonrelativistic incident energies, the first Born approximation is applicable for calculating these data, in which the key physics quantity is the generalized oscillator strength (GOS). In high-energy electron impact excitation processes, atoms will be excited into various excited states including strongly perturbed Rydberg and adjacent continuum states. How to calculate these quantities of a nontrivial many-electron atom rapidly and accurately is still a great challenge. Based on our eigenchannel R -matrix method R -eigen, we further extend it to calculate the GOS of a whole channel in an atom, which includes all Rydberg and adjacent continuum states. The Jπ=1- states of argon are chosen as an illustrating example. The calculation results are in good agreement with the available benchmark absolute experimental measurements. The calculated eigenchannel GOS matrix elements are smooth functions of the excitation energy and momentum transfer. From such smooth eigenchannel GOS matrix elements, we can obtain the GOS of any specific excited state through multichannel quantum defect theory, e.g., infinite Rydberg (including a strongly perturbed one), autoionization, and continuum states.
Low-lying resonances and relativistic screening in Big Bang nucleosynthesis
NASA Astrophysics Data System (ADS)
Famiano, M. A.; Balantekin, A. B.; Kajino, T.
2016-04-01
We explore effects of the screening due to the relativistic electron-positron plasma and presence of resonances in the secondary reactions leading to A =7 nuclei during the Big Bang nucleosynthesis. In particular, we investigate and examine possible low-lying resonances in the 7Be (3He,γ ) 10C reaction and examine the resultant destruction of 7Be for various resonance locations and strengths. While a resonance in the 10C compound nucleus is thought to have negligible effects we explore the possibility of an enhancement from plasma screening that may adjust the final 7Be abundance. We find the effects of relativistic screening and possible low-lying resonances to be relatively small in the standard Early Universe models.
Organic semiconductor interfaces: low-lying lattice modes of pentacene monolayers
NASA Astrophysics Data System (ADS)
He, Rui; Blanchet, Graciela; Pinczuk, Aron
2010-03-01
Highly uniform monolayers of pentacene that are grown on polymeric substrate of poly alpha-methylstyrene exhibit sharp and intense free exciton luminescence. Large enhancements of Raman scattering intensities at the free exciton resonance enable the first observations of low-lying lattice vibration modes in films reaching the single monolayer level.footnotetextRui He, et al. Appl. Phys. Lett. 94, 223310 (2009). The low- lying modes display characteristic changes when going from a single monolayer to two layers, revealing that a phase akin to a thin film phase of pentacene already emerges in structures of only two monolayers. A simple analysis of mode splittings offers estimates of the strength of inter-layer interactions. The results demonstrate novel venues for ultra-thin film characterization and studies of interface effects in organic molecular semiconductor structures.
NASA Astrophysics Data System (ADS)
McPherson, David M.
An inverse kinematic proton scattering experiment was performed at the National Superconducting Cyclotron Laboratory (NSCL) using the GRETINA-S800 detector system in conjunction with the Ursinus College liquid hydrogen target. gamma-ray yields from the experiment were determined using geant4 simulations, generating state population cross sections. These cross sections were used to extract the delta_3 deformation length for the low-lying octupole vibration excitations in Ca-48,49 using the coupled channels analysis code fresco. Particle-core coupling in Ca-49 was studied in comparison to Ca-48 through determination of the neutron and proton deformation lengths. The total inverse kinematic proton scattering deformation lengths were evaluated for the low-lying octupole vibration excitations in Ca-48,49 to be delta_3(Ca-48, 3. -_1) = 1.0(2)fm,delta_3(Ca-49, 9/2. +_1) = 1.2(1)fm, delta_3 (Ca-49, 9/2. +_1) = 1.5(2)fm, delta_3(Ca-49,5/2. +_1) = 1.1(1)fm. Proton and neutron deformation lengths for two of theseoctupole states were also determined to be delta_p(Ca-48, 3. -_1) = 0.9(1)fm,delta_p (Ca-49, 9/2. +_1) = 1.0(1)fm, delta_n(Ca-48, 3. -_1) = 1.1(3)fm, anddelta_n(Ca-49, 9/2. +_1) = 1.3(3)fm. Additionally, the ratios of the neutronto proton transition matrix elements were also determined for these two states to be M_n/M_p(Ca-48, 3. -_1) = 1.7(6) and M_n/M_p(Ca-49, 9/2. +_1) = 2.0(5).Statistically, the derived values for these two nuclei are nearly identical.
Marchal, Rémi; Carbonnière, Philippe; Pouchan, Claude
2015-01-22
The study of atomic clusters has become an increasingly active area of research in the recent years because of the fundamental interest in studying a completely new area that can bridge the gap between atomic and solid state physics. Due to their specific properties, such compounds are of great interest in the field of nanotechnology [1,2]. Here, we would present our GSAM algorithm based on a DFT exploration of the PES to find the low lying isomers of such compounds. This algorithm includes the generation of an intial set of structure from which the most relevant are selected. Moreover, an optimization process, called raking optimization, able to discard step by step all the non physically reasonnable configurations have been implemented to reduce the computational cost of this algorithm. Structural properties of Ga{sub n}Asm clusters will be presented as an illustration of the method.
Dasso, C. H.; Vitturi, A.
2009-03-04
We exploit a model describing the break-up of weakly-bound nuclei that can be used as a laboratory for testing different prescriptions that have been advanced in the literature to take into account the near-by presence of continuum states. In the model we follow the evolution of a single particle wave function in one dimension, initially bound by a Woods-Saxon type potential and then perturbed by a time- and position-dependent external field. Proper choices of this potential can simulate the effect of the interaction between reaction partners in a nuclear collision. These processes generate inelastic excitation probabilities that--distributed over the bound and continuum states of the system--lead to either a partial or a total fragmentation of the final wave function. The comparison with the exact calculations shows that standard coupled channel descriptions based on discretization of the continuum can be accurate only when a proper choice is made of the number of discrete states, of the energy mesh and of the energy cutoff. This may imply, even in simplified cases, the use of a rather large (and unpracticable) number of channels. The use of a more restricted number of channels may lead to misleading results.
{sup 10}Li low-lying resonances populated by one-neutron transfer
Cavallaro, M. Agodi, C.; Carbone, D.; Cunsolo, A.; De Napoli, M.; Cappuzzello, F.; Bondì, M.; Davids, B.; Galinski, N.; Ruiz, C.; Davinson, T.; Sanetullaev, A.; Foti, A.; Kanungo, R.; Lenske, H.; Orrigo, S. E. A.
2015-10-15
The {sup 9}Li + {sup 2}H → {sup 10}Li + {sup 1}H one-neutron transfer reaction has been performed at 100 MeV incident energy at TRIUMF using a {sup 9}Li beam delivered by the ISAC-II facility. A setup based on double-sided silicon strip detectors has been used in order to detect and identify the outgoing {sup 9}Li produced by the {sup 10}Li breakup at forward angles and the recoil protons emitted at backward angles. The {sup 10}Li low-lying resonances, whose energies, widths and configurations are still unclear, have been populated with significant statistics.
Low-Lying Dirac Eigenmodes, Topological Charge Fluctuations and the Instanton Liquid Model
I. Horvath; S.J. Dong; T. Draper; F.X. Lee; H.B. Thacker; J.B. Zhang
2002-05-01
The local structure of low-lying eigenmodes of the overlap Dirac operator is studied. It is found that these modes cannot be described as linear combinations of 't Hooft ''would-be'' zeromodes associated with instanton excitations that underly the Instanton Liquid Model. This implies that the instanton liquid scenario for spontaneous chiral symmetry breaking in QCD is not accurate. More generally, our data suggests that the vacuum fluctuations of topological charge are not effectively dominated by localized lumps of unit charge with which the topological ''would-be'' zeromodes could be associated.
10Li low-lying resonances populated by one-neutron transfer
NASA Astrophysics Data System (ADS)
Cavallaro, M.; De Napoli, M.; Cappuzzello, F.; Agodi, C.; Bondı, M.; Carbone, D.; Cunsolo, A.; Davids, B.; Davinson, T.; Foti, A.; Galinski, N.; Kanungo, R.; Lenske, H.; Orrigo, S. E. A.; Ruiz, C.; Sanetullaev, A.
2015-10-01
The 9Li + 2H → 10Li + 1H one-neutron transfer reaction has been performed at 100 MeV incident energy at TRIUMF using a 9Li beam delivered by the ISAC-II facility. A setup based on double-sided silicon strip detectors has been used in order to detect and identify the outgoing 9Li produced by the 10Li breakup at forward angles and the recoil protons emitted at backward angles. The 10Li low-lying resonances, whose energies, widths and configurations are still unclear, have been populated with significant statistics.
STS-31 Discovery, OV-103, rockets through low-lying clouds after KSC liftoff
NASA Technical Reports Server (NTRS)
1990-01-01
STS-31 Discovery, Orbiter Vehicle (OV) 103, rides above the firey glow of the solid rocket boosters (SRBs) and space shuttle main engines (SSMEs) and a long trail of exhaust as it heads toward Earth orbit. Kennedy Space Center (KSC) Launch Complex (LC) Pad 39B is covered in an exhaust cloud moments after the liftoff of OV-103 at 8:33:51.0492 am (Eastern Daylight Time (EDT)). The exhaust plume pierces the low-lying clouds as OV-103 soars into the clear skies above. A nearby waterway appears in the foreground.
STS-31 Discovery, OV-103, is hidden in low-lying clouds after KSC liftoff
NASA Technical Reports Server (NTRS)
1990-01-01
STS-31 Discovery, Orbiter Vehicle (OV) 103, is hidden in low-lying cloud cover as it rises above Kennedy Space Center (KSC) Launch Complex (LC) Pad 39B just after its liftoff at 8:33:51.0492 am (Eastern Daylight Time (EDT)). The glow of the solid rocket booster (SRB) and the space shuttle main engine (SSME) firings appears just below the cloud cover and is reflected in the nearby waterway (foreground). An exhaust plume trails from OV-103 and its SRBs and covers the launch pad area.
A numerical study of the thermal stability of low-lying coronal loops
NASA Technical Reports Server (NTRS)
Klimchuk, J. A.; Antiochos, S. K.; Mariska, J. T.
1986-01-01
The nonlinear evolution of loops that are subjected to a variety of small but finite perturbations was studied. Only the low-lying loops are considered. The analysis was performed numerically using a one-dimensional hydrodynamical model developed at the Naval Research Laboratory. The computer codes solve the time-dependent equations for mass, momentum, and energy transport. The primary interest is the active region filaments, hence a geometry appropriate to those structures was considered. The static solutions were subjected to a moderate sized perturbation and allowed to evolve. The results suggest that both hot and cool loops of the geometry considered are thermally stable against amplitude perturbations of all kinds.
Nucleosynthesis of 92Nb and the relevance of the low-lying isomer at 135.5 keV
NASA Astrophysics Data System (ADS)
Mohr, Peter
2016-06-01
Background: Because of its half-life of about 35 million years, 92Nb is considered as a chronometer for nucleosynthesis events prior to the birth of our sun. The abundance of 92Nb in the early solar system can be derived from meteoritic data. It has to be compared to theoretical estimates for the production of 92Nb to determine the time between the last nucleosynthesis event before the formation of the early solar system. Purpose: The influence of a low-lying short-lived isomer on the nucleosynthesis of 92Nb is analyzed. The thermal coupling between the ground state and the isomer via so-called intermediate states affects the production and survival of 92Nb. Method: The properties of the lowest intermediate state in 92Nb are known from experiment. From the lifetime of the intermediate state and from its decay branchings, the transition rate from the ground state to the isomer and the effective half-life of 92Nb are calculated as functions of the temperature. Results: The coupling between the ground state and the isomer is strong. This leads to thermalization of ground state and isomer in the nucleosynthesis of 92Nb in any explosive production scenario and almost 100% survival of 92Nb in its ground state. However, the strong coupling leads to a temperature-dependent effective half-life of 92Nb which makes the 92Nb survival very sensitive to temperatures as low as about 8 keV, thus turning 92Nb at least partly into a thermometer. Conclusions: The low-lying isomer in 92Nb does not affect the production of 92Nb in explosive scenarios. In retrospect this validates all previous studies where the isomer was not taken into account. However, the dramatic reduction of the effective half-life at temperatures below 10 keV may affect the survival of 92Nb after its synthesis in supernovae, which are the most likely astrophysical sites for the nucleosynthesis of 92Nb.
Critical field enhancement of asymptotic optical bound states in the continuum
Yoon, Jae Woong; Song, Seok Ho; Magnusson, Robert
2015-01-01
We study spectral singularities and critical field enhancement factors associated with embedded photonic bound states in subwavelength periodic Si films. Ultrahigh-Q resonances supporting field enhancement factor exceeding 108 are obtained in the spectral vicinity of exact embedded eigenvalues in spite of deep surface modulation and vertical asymmetry of the given structure. Treating relations between the partial resonance Q and field enhancement factors with an analytical coupled-mode model, we derive a general strategy to maximize the field enhancement associated with these photonic bound states in the presence of material dissipation. The analytical expression for the field enhancement quantitatively agrees with rigorous numerical calculations. Therefore, our results provide a general knowledge for designing practical resonance elements based on optical bound states in the continuum in various applications. PMID:26673548
Critical field enhancement of asymptotic optical bound states in the continuum.
Yoon, Jae Woong; Song, Seok Ho; Magnusson, Robert
2015-01-01
We study spectral singularities and critical field enhancement factors associated with embedded photonic bound states in subwavelength periodic Si films. Ultrahigh-Q resonances supporting field enhancement factor exceeding 10(8) are obtained in the spectral vicinity of exact embedded eigenvalues in spite of deep surface modulation and vertical asymmetry of the given structure. Treating relations between the partial resonance Q and field enhancement factors with an analytical coupled-mode model, we derive a general strategy to maximize the field enhancement associated with these photonic bound states in the presence of material dissipation. The analytical expression for the field enhancement quantitatively agrees with rigorous numerical calculations. Therefore, our results provide a general knowledge for designing practical resonance elements based on optical bound states in the continuum in various applications. PMID:26673548
Critical field enhancement of asymptotic optical bound states in the continuum
NASA Astrophysics Data System (ADS)
Yoon, Jae Woong; Song, Seok Ho; Magnusson, Robert
2015-12-01
We study spectral singularities and critical field enhancement factors associated with embedded photonic bound states in subwavelength periodic Si films. Ultrahigh-Q resonances supporting field enhancement factor exceeding 108 are obtained in the spectral vicinity of exact embedded eigenvalues in spite of deep surface modulation and vertical asymmetry of the given structure. Treating relations between the partial resonance Q and field enhancement factors with an analytical coupled-mode model, we derive a general strategy to maximize the field enhancement associated with these photonic bound states in the presence of material dissipation. The analytical expression for the field enhancement quantitatively agrees with rigorous numerical calculations. Therefore, our results provide a general knowledge for designing practical resonance elements based on optical bound states in the continuum in various applications.
Imaging of continuum states of the He{sub 2}{sup 2+} quasimolecule
Schmidt, L. Ph. H.; Schoeffler, M. S.; Stiebing, K. E.; Schmidt-Boecking, H.; Doerner, R.; Afaneh, F.; Weber, Th.
2007-07-15
Using cold target recoil ion momentum spectroscopy (COLTRIMS) we have investigated the production of one free electron in slow He{sup 2+}+He(1s{sup 2}) collisions. At projectile velocities between 0.6 and 1.06 a.u. (9-28 keV/u), the fully differential cross section was measured state selective with respect to the second electron, which is bound either at the target or the projectile. We provide a comprehensive data set comprising state selective total cross section, scattering angle dependent single differential cross sections, and fully differential cross section. We show that the momentum distribution of the electron in the continuum image the relevant molecular orbitals for the reaction channel under consideration. By choosing the bound electron final state at the target or projectile and the impact parameter we can select these orbitals and manipulate their relative phase.
On the nature of an emergent symmetry in QCD with low-lying Dirac modes removed
NASA Astrophysics Data System (ADS)
Cohen, Thomas D.
2016-02-01
Remarkable symmetry properties appear to arise in lattice calculations of correlation functions in which the lowest-lying eigenmodes of the Dirac operator in quark propagators are removed by hand. The Banks-Casher relation ties the chiral condensate to the density of low-lying modes; thus, it is plausible that removal of such modes could lead to a regime where spontaneous chiral symmetry breaking does not occur. Surprising, a pattern of identical correlation functions was observed that is larger than can be explained by a restoration of chiral symmetry. This suggests that a larger symmetry—one that is not present in the QCD Lagrangian—emerges when these modes are removed. Previously it was argued that this emergent symmetry was SU(4). However, when the low-lying modes are removed, the correlation functions of sources in the SU(4) 15-plet of spin-1 mesons appear to coincide with the correlation function of the SU(4) singlet. A natural explanation for this is an emergent symmetry larger than SU(4). In this work, it is shown that there exists no continuous symmetry whose generators in the field theory are spatial integrals of local operators that can account for the full pattern of identical correlation functions unless the apparent coincidence of the singlet channel with the 15-plet is accidental.
Gao, Xingwei; Hsu, Chia Wei; Zhen, Bo; Lin, Xiao; Joannopoulos, John D; Soljačić, Marin; Chen, Hongsheng
2016-01-01
We develop a formalism, based on the mode expansion method, to describe the guided resonances and bound states in the continuum (BICs) in photonic crystal slabs with one-dimensional periodicity. This approach provides analytic insights to the formation mechanisms of these states: the guided resonances arise from the transverse Fabry-Pérot condition, and the divergence of the resonance lifetimes at the BICs is explained by a destructive interference of radiation from different propagating components inside the slab. We show BICs at the center and on the edge of the Brillouin zone protected by symmetry, BICs at generic wave vectors not protected by symmetry, and the annihilation of BICs at low-symmetry wave vectors. PMID:27557882
Catching the bound states in the continuum of a phantom atom in graphene
NASA Astrophysics Data System (ADS)
Guessi, L. H.; Machado, R. S.; Marques, Y.; Ricco, L. S.; Kristinsson, K.; Yoshida, M.; Shelykh, I. A.; de Souza, M.; Seridonio, A. C.
2015-07-01
We explore theoretically the formation of bound states in the continuum (BICs) in graphene hosting two collinear adatoms situated at different sides of the sheet and at the center of the hexagonal cell, where a phantom atom of a fictitious lattice emulates the six carbons of the cell. We verify that in this configuration the local density of states near the Dirac points exhibits two characteristic features: (i) a cubic dependence on energy instead of a linear one for graphene as found in New J. Phys. 16, 013045 (2014), 10.1088/1367-2630/16/1/013045, and (ii) the formation of BICs as an aftermath of a Fano destructive interference assisted by the Coulomb correlations in the adatoms. For the geometry where adatoms are collinear to carbon atoms, we report an absence of BICs.