TY - JOUR

T1 - Multidimensional anharmonic calculation of the vibrational frequencies and intensities for the trans and cis isomers of HONO with the use of normal coordinates

AU - Bulychev, V. P.

AU - Tokhadze, K. G.

PY - 2004/12/1

Y1 - 2004/12/1

N2 - The equilibrium geometry and the potential energy and dipole moment surfaces have been determined for the cis and trans isomers of the HONO molecule by an ab initio Moller-Plesset (MP2) calculation with a wide set of atomic orbitals. The multidimensional anharmonic vibrational Schrodinger equations are solved using the variational method with the Hamiltonian and wave functions written in the normal coordinates of cis and trans isomers. All one- and two-dimensional and a number of three-dimensional vibrational problems are solved to obtain the energy levels and vibrational eigenfunctions. The frequencies and intensities for the fundamental, overtone and some combination bands are determined in good agreement with the available experimental results. The calculation shows the strength of coupling between different vibrational modes and reveals the presence of strong resonances between the (v1, v3, v6) and (v1, v3-1, v 6+2) states of cis-HONO. This fact may be important for understanding the energy redistribution between the intermolecular degrees of freedom. The magnitude and direction of vibrationally averaged ground-state dipole moment of both isomers, as well as the direction of transition dipole moments, are in good agreement with the experimental findings. The changes in the values of dipole moment and some geometrical parameters of cis- and trans-HONO on vibrational excitation are also computed. © 2004 Elsevier B.V. All rights reserved.

AB - The equilibrium geometry and the potential energy and dipole moment surfaces have been determined for the cis and trans isomers of the HONO molecule by an ab initio Moller-Plesset (MP2) calculation with a wide set of atomic orbitals. The multidimensional anharmonic vibrational Schrodinger equations are solved using the variational method with the Hamiltonian and wave functions written in the normal coordinates of cis and trans isomers. All one- and two-dimensional and a number of three-dimensional vibrational problems are solved to obtain the energy levels and vibrational eigenfunctions. The frequencies and intensities for the fundamental, overtone and some combination bands are determined in good agreement with the available experimental results. The calculation shows the strength of coupling between different vibrational modes and reveals the presence of strong resonances between the (v1, v3, v6) and (v1, v3-1, v 6+2) states of cis-HONO. This fact may be important for understanding the energy redistribution between the intermolecular degrees of freedom. The magnitude and direction of vibrationally averaged ground-state dipole moment of both isomers, as well as the direction of transition dipole moments, are in good agreement with the experimental findings. The changes in the values of dipole moment and some geometrical parameters of cis- and trans-HONO on vibrational excitation are also computed. © 2004 Elsevier B.V. All rights reserved.

KW - Anharmonic variational calculation

KW - Frequencies and intensities of vibrational bands

KW - Molecular structure

KW - Nitrous acid

UR - http://www.scopus.com/inward/record.url?scp=6944226839&partnerID=8YFLogxK

U2 - 10.1016/j.molstruc.2004.01.072

DO - 10.1016/j.molstruc.2004.01.072

M3 - Article

AN - SCOPUS:6944226839

VL - 708

SP - 47

EP - 54

JO - Journal of Molecular Structure

JF - Journal of Molecular Structure

SN - 0022-2860

IS - 1-3

ER -