The Lyman and Werner bands of H2

1984 ◽  
Vol 62 (12) ◽  
pp. 1639-1664 ◽  
Author(s):  
I. Dabrowski
Keyword(s):  
Ab Initio ◽  
Vacuum Ultraviolet ◽  
Energy Levels ◽  
Vibration Energy ◽  
Dissociation Limit ◽  
Convergence Error ◽  
Ab Initio Theory ◽  
Vibrational Levels ◽  
Low Energies ◽  
State Formula

The Lyman and Werner bands of H2 have been measured under high resolution in the vacuum ultraviolet from 1000 to 1650 Å. Flash discharge spectra, both in absorption and in emission, have allowed an extension of the analysis to include most of the rotation–vibration levels of the ground state ([Formula: see text], ν = 0 to 14, J = 0 to 29). The C1Πu state has been observed from ν = 0–13, and the [Formula: see text] state from ν = 0–17, including highly rotationally excited levels for ν = 0–6. The resulting rotation–vibration energy levels are accurate to 0.1 cm−1.The agreement between observation and ab initio theory is now very good. The deviations of the vibrational levels are very close to zero for low ν, but increase to 0.3 cm−1 for high ν. The ab initio calculations are somewhat less accurate for the rotational levels. The deviations are close to zero for low J, but increase to 4 cm−1 for high J, that is, for energy levels close to the dissociation limit. It can also be seen that the convergence error in the Born–Oppenheimer calculation is small (~0.1 cm−1) at low energies, but approaches 1 cm−1 near the dissociation limit.

The absorption and emission spectra of HD in the vacuum ultraviolet

1976 ◽  
Vol 54 (5) ◽  
pp. 525-567 ◽  
Author(s):  
I. Dabrowski ◽  
G. Herzberg
Keyword(s):  
Absorption Spectrum ◽  
Ab Initio ◽  
Excited States ◽  
Vacuum Ultraviolet ◽  
Emission Spectra ◽  
Dissociation Limit ◽  
Infinite Mass ◽  
Ab Initio Theory ◽  
Vibrational Constants ◽  
Weak Transitions

The absorption spectrum of HD has been studied under high resolution in the vacuum ultraviolet to 840 Å, the emission spectrum to 1000 Å. The analysis of the latter gives accurate rotational constants and vibrational intervals of the ground state right up to the dissociation limit. Comparing these experimental data with calculations from ab initio theory, agreement to the same extent as was previously found for H2 and D2 is obtained. Extrapolation of the obs. – calc. values from H2 and D2 to infinite mass yields agreement with the recently revised theoretical values to within less than 0.1 for v < 7 and less than 0.5 cm−1 for the whole range of observed v values. The deviations for finite mass (H2 and D2) are clearly due to the non-adiabatic corrections neglected in the ab initio calculations. The results for HD are not halfway between H2 and D2 but are closer to H2. This apparent anomaly can be quantitatively accounted for, on the basis of recent calculations of Wolniewicz, by the effect of additional nonadiabatic corrections caused by the excited Σu states which in HD, unlike H2 and D2, can interact with the ground state.The rotational and vibrational constants of the excited states B1Σu+, C1Πu, and B′1Σu+ show somewhat larger deviations from ab initio values ranging for v0v from 5 to 120 cm−1, just as for H2 and D2. The electronic isotope shift of HD lies approximately half-way between the values of H2 and D2 as expected. In addition to the B–X, C–X, and B′–X systems the absorption spectrum of HD, unlike that of H2 and D2, shows an extensive progression of weak transitions to the double minimum state EF1Σg+ and a few very weak transitions to the G1Σg+ and I1Πg states. For the EF state both levels in the outer minimum (F) and levels above the maximum are observed. The correlation of the six excited states B, C, B′, EF, G, and I to the two close-lying dissociation limits corresponding to H + D* and H* + D is briefly discussed.

The Absorption Spectrum of D2 from 1100 to 840 Å

1974 ◽  
Vol 52 (12) ◽  
pp. 1110-1136 ◽  
Author(s):  
I. Dabrowski ◽  
G. Herzberg
Keyword(s):  
Absorption Spectrum ◽  
High Resolution ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Detailed Comparison ◽  
Electronic Energy ◽  
Dissociation Limit ◽  
Convergence Error ◽  
Vibrational Levels ◽  
Vibrational Constants

The absorption spectrum of D2 has been studied in absorption at high resolution (0.254 Å/mm) in the region 1100 to 840 Å. The three band systems B1Σu+ ← X1Σg+ (Lyman bands), B′ 1Σu+ ← X1Σg+ and C1Πu ← X1Σg (Werner bands) have been measured right up to the dissociation limit. New improved values of the rotational and vibrational constants in the three upper states have been derived. By comparing the electronic energy differences Tc thus obtained with the corresponding values for H2 fairly precise values for the electronic isotope shifts for the B–X and C–X systems have been determined (+ 2.8 and −7.4 cm−1 respectively). In this connection two gaps in the knowledge of the absorption spectrum of H2 have been filled: the Lyman bands with ν′ = 5–16 and the Werner bands with ν′ = 0–4 (see Appendix). A detailed comparison is made of the observed vibrational levels and the observed Bν values of D2 with those derived from ab initio calculations based on the Kotos and Wolniewicz' potential functions. From the observed electronic isotope shift the adiabatic corrections can be estimated near the minimum. For the B state these estimates agree very well with the ab initio calculations. The remaining differences between observation and theory are partly due to lack of convergence of the Born–Oppenheimer calculation, partly to the neglect of nonadiabatic corrections. The convergence error near minimum is estimated to be 5.1 cm−1 for the B state and 1.2 cm−1 for the C state.

THE LYMAN BANDS OF MOLECULAR HYDROGEN

1959 ◽  
Vol 37 (5) ◽  
pp. 636-659 ◽  
Author(s):  
G. Herzberg ◽  
L. L. Howe
Keyword(s):  
High Resolution ◽  
Vibrational Level ◽  
Ground State ◽  
Molecular Hydrogen ◽  
Equilibrium Constants ◽  
Dissociation Limit ◽  
Vibrational Levels ◽  
State Formula ◽  
Single Formula ◽  
Vibrational Constants

The Lyman bands of H2 have been investigated under high resolution with a view to improving the rotational and vibrational constants of H2 in its ground state. Precise Bv and ΔG values have been obtained for all vibrational levels of the ground state. One or two of the highest rotational levels of the last vibrational level (v = 14) lie above the dissociation limit. Both the [Formula: see text] and ΔG″ curves have a point of inflection at about v″ = 3. This makes it difficult to represent the whole course of each of these curves by a single formula and therefore makes the resulting equilibrium constants somewhat uncertain. This uncertainty is not very great for the rotational constants for which we find[Formula: see text]but is considerable for the vibrational constants ωe and ωexe for which three-, four-, five-, and six-term formulae give results diverging by ± 1 cm−1. The rotational and vibrational constants for the upper state [Formula: see text] of the Lyman bands are also determined. An appreciable correction to the position of the upper state is found.

Calculation of Rotation–Vibration Energy Levels of the Water Molecule with Near-Experimental Accuracy Based on an ab Initio Potential Energy Surface

2013 ◽  
Vol 117 (39) ◽  
pp. 9633-9643 ◽  
Author(s):  
Oleg L. Polyansky ◽  
Roman I. Ovsyannikov ◽  
Aleksandra A. Kyuberis ◽  
Lorenzo Lodi ◽  
Jonathan Tennyson ◽  
...  
Keyword(s):  
Water Molecule ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Energy Surface ◽  
Energy Levels ◽  
Vibration Energy ◽  
Experimental Accuracy

scholarly journals Computational study of the rovibrational spectrum of H2O-HF

2021 ◽  
Author(s):  
Dominika VIGLASKA ◽  
Xiao-Gang Wang ◽  
Tucker CARRINGTON ◽  
David Tew
Keyword(s):  
Experimental Data ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Energy Surface ◽  
Computational Study ◽  
Energy Levels ◽  
Dissociation Limit ◽  
Lanczos Algorithm ◽  
Vibrational States

In this paper we report rovibrational energy levels, transition frequencies, and intensities computed for H2O-HF using a new ab initio potential energy surface and compare with available experimental data. We use the rigid monomer approximation. A G4 symmetry-adapted Lanczos algorithm and an uncoupled product basis are employed. The rovibrational levels are computed up to J = 4. The new analytic 9-D potential is �t to 39771 counterpoise corrected CCSD(T)(F12*)/augcc- pVTZ energies and reduces to the sum of uncoupled H2O and HF potentials in the dissociation limit. On the new potential better agreement with experiment is obtained by re-assigning the R(1) transitions of two vibrational states.

Ab Initio Predicted Rotation-Vibration Energy Levels of HeH+2

1995 ◽  
Vol 172 (1) ◽  
pp. 265-274 ◽  
Author(s):  
V. Spirko ◽  
W.P. Kraemer
Keyword(s):  
Ab Initio ◽  
Energy Levels ◽  
Vibration Energy

scholarly journals Ab initio rotation–vibration energy levels of triatomics to spectroscopic accuracy

2002 ◽  
Vol 58 (4) ◽  
pp. 663-672 ◽  
Author(s):  
Jonathan Tennyson ◽  
Paolo Barletta ◽  
Maxim A Kostin ◽  
Oleg L Polyansky ◽  
Nikolai F Zobov
Keyword(s):  
Ab Initio ◽  
Energy Levels ◽  
Vibration Energy

scholarly journals Ab initio theory of the negatively charged boron vacancy qubit in hexagonal boron nitride

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Viktor Ivády ◽  
Gergely Barcza ◽  
Gergő Thiering ◽  
Song Li ◽  
Hanen Hamdi ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Ab Initio ◽  
Density Functional ◽  
Hexagonal Boron Nitride ◽  
Energy Levels ◽  
Quantum Bits ◽  
Density Matrix Renormalization ◽  
Ab Initio Theory ◽  
Optically Detected ◽  
Highly Correlated

AbstractHighly correlated orbitals coupled with phonons in two-dimension are identified for paramagnetic and optically active boron vacancy in hexagonal boron nitride by first principles methods which are responsible for recently observed optically detected magnetic resonance signal. Here, we report ab initio analysis of the correlated electronic structure of this center by density matrix renormalization group and Kohn-Sham density functional theory methods. By establishing the nature of the bright and dark states as well as the position of the energy levels, we provide a complete description of the magneto-optical properties and corresponding radiative and non-radiative routes which are responsible for the optical spin polarization and spin dependent luminescence of the defect. Our findings pave the way toward advancing the identification and characterization of room temperature quantum bits in two-dimensional solids.

An ab initio investigation of the potential function and rotation–vibration energies of NH3

1984 ◽  
Vol 62 (12) ◽  
pp. 1801-1805 ◽  
Author(s):  
P. R. Bunker ◽  
W. P. Kraemer ◽  
V. Špirko
Keyword(s):  
Potential Energy ◽  
Ab Initio ◽  
Potential Function ◽  
Energy Surface ◽  
Energy Levels ◽  
Vibration Energy ◽  
Interaction Technique ◽  
Equilibrium Bond Length ◽  
Analytic Potential ◽  
Anharmonic Force

Fifty-four points on the potential energy surface of the ground electronic state of the ammonia molecule, with energies up to 9700 cm–1 above equilibrium, have been calculated ab initio using the configuration interaction technique. An analytic potential function has been fitted through these points and the rotation–vibration energy levels have been calculated using the nonrigid invertor Hamiltonian. The agreement with experiment is satisfactory enough that the anharmonic force constants obtained can be realistically used to assist in the interpretation of anharmonicity effects in the spectrum. We calculate the equilibrium bond length as 1.016 Å, the equilibrium HNH angle as 106.2°, and the invertion barrier as 1995 cm−1.

An ab initio study of the rotation—vibration energy levels of GeH2 in the ā3B1 state

1985 ◽  
Vol 118 (1) ◽  
pp. 60-63 ◽  
Author(s):  
R.A. Phillips ◽  
R.J. Buenker ◽  
R. Beardsworth ◽  
P.R. Bunker ◽  
Per Jensen ◽  
...  
Keyword(s):  
Ab Initio ◽  
Energy Levels ◽  
Vibration Energy ◽  
Ab Initio Study
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