Accuracy of XH-stretching intensities with the Deng–Fan potential

TY - JOUR

T1 - Accuracy of XH-stretching intensities with the Deng–Fan potential

AU - Vogt, Emil

AU - Sage, Daniel S.

AU - Kjaergaard, Henrik G.

PY - 2019

Y1 - 2019

N2 - One-dimensional local mode XH-stretching (X = 16O, 19F and 35Cl) vibrational transition frequencies and intensities have been calculated for six small atmospheric relevant molecules. The calculations are done using Morse, Deng–Fan and numeric potentials at the CCSD(T)/aug-cc-pVTZ level of theory. Parameters of the Morse potential are found from the derivatives of the potential energy surface, with respect to the internal XH-stretching displacement coordinate, evaluated at the equilibrium geometry. Parameters of the Deng–Fan potential are obtained using the first two transition frequencies of the Morse potential. The dipole moment functions (DMFs) are represented by a sixth-order polynomial in the displacement coordinate fitted to dipole moment single points calculated with a finite field approach. Analytical matrix elements are derived and used to calculate oscillator strengths for the Morse and Deng–Fan potential. We compare calculated and experimentally determined oscillator strengths and transition frequencies, as well as displacement matrix elements of the different potentials. For the XH-stretching vibrations considered, the Deng–Fan potential predicts absorption intensities considerably better than the Morse potential.

AB - One-dimensional local mode XH-stretching (X = 16O, 19F and 35Cl) vibrational transition frequencies and intensities have been calculated for six small atmospheric relevant molecules. The calculations are done using Morse, Deng–Fan and numeric potentials at the CCSD(T)/aug-cc-pVTZ level of theory. Parameters of the Morse potential are found from the derivatives of the potential energy surface, with respect to the internal XH-stretching displacement coordinate, evaluated at the equilibrium geometry. Parameters of the Deng–Fan potential are obtained using the first two transition frequencies of the Morse potential. The dipole moment functions (DMFs) are represented by a sixth-order polynomial in the displacement coordinate fitted to dipole moment single points calculated with a finite field approach. Analytical matrix elements are derived and used to calculate oscillator strengths for the Morse and Deng–Fan potential. We compare calculated and experimentally determined oscillator strengths and transition frequencies, as well as displacement matrix elements of the different potentials. For the XH-stretching vibrations considered, the Deng–Fan potential predicts absorption intensities considerably better than the Morse potential.

KW - Deng–Fan analytical matrix elements

KW - Morse potential

KW - Vibrational transitions

UR - http://www.scopus.com/inward/record.url?scp=85053483473&partnerID=8YFLogxK

U2 - 10.1080/00268976.2018.1521529

DO - 10.1080/00268976.2018.1521529

M3 - Journal article

AN - SCOPUS:85053483473

SN - 0026-8976

VL - 117

SP - 1629

EP - 1639

JO - Molecular Physics

JF - Molecular Physics

IS - 13

ER -