Photodissociation of HOBr. I. Ab initio potential energy surfaces for the three lowest electronic states and calculation of rotational–vibrational energy levels and wave functions

1999 ◽  
Vol 110 (17) ◽  
pp. 8448-8460 ◽  
Author(s):  
László Füsti-Molnár ◽  
Péter G. Szalay ◽  
Gabriel G. Balint-Kurti
Keyword(s):  
Potential Energy ◽  
Ab Initio ◽  
Potential Energy Surfaces ◽  
Vibrational Energy ◽  
Energy Levels ◽  
Electronic States ◽  
Wave Functions ◽  
Vibrational Energy Levels ◽  
Energy Surfaces

Vibrational energies of H3+ and Li3+ based on the diatomics-in-molecules potentials

1986 ◽  
Vol 51 (10) ◽  
pp. 2057-2062 ◽  
Author(s):  
Jan Vojtík ◽  
Vladimír Špirko ◽  
Per Jensen
Keyword(s):  
Potential Energy ◽  
Ab Initio ◽  
Potential Energy Surfaces ◽  
Vibrational Energy ◽  
Energy Levels ◽  
Vibrational Motion ◽  
Variational Calculations ◽  
Vibrational Energies ◽  
Vibrational Energy Levels ◽  
Energy Surfaces

The present publication reports variational calculations of the vibrational energy levels for H3+, D3+, 6Li3+, and 7Li3+, starting from potential energy surfaces generated by the DIM scheme. The vibrational energies obtained agree semiquantitatively with those based on the best ab initio potentials available. The results seem to indicate that an analogous approach might be useful in describing the vibrational motion of heavier alkali cluster cations A3+.

scholarly journals New ab Initio Potential Energy Surfaces for the Renner-Teller Coupled 11A′ and 11A′′ States of CH2

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Haitao Ma ◽  
Chunfang Zhang ◽  
Zhijun Zhang ◽  
Xiaojun Liu ◽  
Wensheng Bian
Keyword(s):  
Potential Energy ◽  
Ab Initio ◽  
Potential Energy Surfaces ◽  
Energy Levels ◽  
Electronic States ◽  
Nonlinear Least Squares ◽  
Basis Set ◽  
Least Squares Fit ◽  
Three Body ◽  
Energy Surfaces

New ab initio potential energy surfaces (PESs) for the two lowest-lying singlet 11A′ and 11A′′ electronic states of CH2, coupled by the Renner-Teller (RT) effect and meant for the spectroscopic study, are presented. The surfaces are constructed using a dual-level strategy. The internally contracted multireference configuration interaction calculations with the Davidson correction, using the aug-cc-pVQZ basis set, are employed to obtain 3042 points at the lower level. The core and core-valence correlation effects are taken into account in the ab initio calculations with a modified optimized aug-cc-pCVQZ basis set for the higher-level points. The analytical representations of these PESs, with the inclusion of the nonadiabatic RT terms, are obtained by the nonlinear least-squares fit of the calculated points to three-body expansion. Quantum dynamical calculations are performed on these PESs, and the computed vibronic energy levels for the two singlet electronic states are in excellent agreement with experiment.

scholarly journals High-accuracy water potential energy surface for the calculation of infrared spectra

2018 ◽  
Vol 376 (2115) ◽  
pp. 20170149 ◽  
Author(s):  
Irina I. Mizus ◽  
Aleksandra A. Kyuberis ◽  
Nikolai F. Zobov ◽  
Vladimir Yu. Makhnev ◽  
Oleg L. Polyansky ◽  
...  
Keyword(s):  
Potential Energy ◽  
Ab Initio ◽  
Small Molecules ◽  
Potential Energy Surfaces ◽  
Energy Surface ◽  
Energy Levels ◽  
High Accuracy ◽  
Wave Functions ◽  
Line Intensities ◽  
Energy Surfaces

Transition intensities for small molecules such as water and CO 2 can now be computed with such high accuracy that they are being used to systematically replace measurements in standard databases. These calculations use high-accuracy ab initio dipole moment surfaces and wave functions from spectroscopically determined potential energy surfaces (PESs). Here, an extra high-accuracy PES of the water molecule (H 2 16 O) is produced starting from an ab initio PES which is then refined to empirical rovibrational energy levels. Variational nuclear motion calculations using this PES reproduce the fitted energy levels with a standard deviation of 0.011 cm −1 , approximately three times their stated uncertainty. The use of wave functions computed with this refined PES is found to improve the predicted transition intensities for selected (problematic) transitions. A new room temperature line list for H 2 16 O is presented. It is suggested that the associated set of line intensities is the most accurate available to date for this species. This article is part of the theme issue ‘Modern theoretical chemistry’.

scholarly journals Ab Initio Potential Energy Surfaces for Both the Ground (X̃1A′) and Excited (A∼1A′′) Electronic States of HSiBr and the Absorption and Emission Spectra of HSiBr/DSiBr

2012 ◽  
Vol 2012 ◽  
pp. 1-20 ◽  
Author(s):  
Anyang Li ◽  
Sen Lin ◽  
Daiqian Xie
Keyword(s):  
Potential Energy ◽  
Ab Initio ◽  
Potential Energy Surfaces ◽  
Vibrational Energy ◽  
Electronic States ◽  
Emission Spectra ◽  
Basis Set ◽  
Absorption And Emission ◽  
Absorption And Emission Spectra ◽  
Energy Surfaces

Ab initio potential energy surfaces for the ground (X̃1A′) and excited (A˜A′′1) electronic states of HSiBr were obtained by using the single and double excitation coupled-cluster theory with a noniterative perturbation treatment of triple excitations and the multireference configuration interaction with Davidson correction, respectively, employing an augmented correlation-consistent polarized valence quadruple zeta basis set. The calculated vibrational energy levels of HSiBr and DSiBr of the ground and excited electronic states are in excellent agreement with the available experimental band origins. In addition, the absorption and emission spectra of HSiBr and DSiBr were calculated using an efficient single Lanczos propagation method and are in good agreement with the available experimental observations.

Ab Initio Calculations of Vibrational Energy Levels and Transition Dipole Moments of CO2 Molecules

2008 ◽  
Author(s):  
Zhi Liang ◽  
Hai-Lung Tsai
Keyword(s):  
Ab Initio ◽  
Vibrational Energy ◽  
Molecular Spectroscopy ◽  
Dipole Moments ◽  
Energy Levels ◽  
Wave Functions ◽  
Molecular Vibration ◽  
Transition Dipole ◽  
Transition Dipole Moments ◽  
Vibrational Energy Levels

Ab initio MD simulation of laser-matter interactions is a hot area in the study of the mechanisms of photo-dissociation, photo-ionization and laser induced chemical reactions. The major problems in the study of laser-molecule interactions are to determine the energies and wave functions of molecular vibration states and the molecular transition dipole moments. An efficient method is presented to calculate the intramolecular potential energies and electrical dipole moments of CO2 molecules at the electronic ground state by solving the Kohn-Sham (KS) equation for a total of 101,992 nuclear configurations. The Projector-Augmented Wave (PAW) exchange-correlation potential functionals and Plane Wave (PW) basis functions were used in solving the KS equation. The calculated intra-molecular potential function was then included in the pure vibrational Schro¨dinger equation to determine the vibrational energy eigen values and eigen functions. The vibrational wave functions combined with the calculated dipole moment function were used to determine the transition dipole moments. The calculated results have a good agreement with experimental values. These results can be further used to determinations of molecular spectroscopy and laser absorption coefficients.

Coupled ab initio potential energy surfaces for the two lowest 2A′ electronic states of the C2H molecule

2000 ◽  
Vol 98 (23) ◽  
pp. 1925-1938 ◽  
Author(s):  
M. BOGGIO-PASQUA ◽  
A. I. VORONIN ◽  
PH. HALVICK ◽  
J.-C. RAYEZ ◽  
A. J. C. VARANDAS
Keyword(s):  
Potential Energy ◽  
Ab Initio ◽  
Potential Energy Surfaces ◽  
Electronic States ◽  
Energy Surfaces
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