IR and Raman intensities in vibrational spectra from direct ab initio molecular dynamics: D2O as an illustration

Misako Aida, Michel Dupuis

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

We illustrate the use of quasi-classical direct molecular dynamics on accurate electron-correlated ab initio potential energy surfaces to extract infrared and Raman intensities in addition to the vibrational density of states of a molecular system. We applied the method to deuterated water D2O using the ab initio MP2 level of electronic structure theory. The initial conditions of kinetic and potential energies of the trajectories were chosen to be consistent with the level v = 0 of the harmonic normal modes. We obtained the density of states and the IR and Raman intensities by means of the Fourier transforms of the autocorrelation functions of the velocities, dipole moment time-derivatives, and polarizability tensor time-second-derivatives, respectively. The calculated spectrum is in excellent quantitative agreement with the experimentally observed spectrum. The method holds promise to obtain very accurate simulated spectra for small molecules, including IR and Raman intensities. Extensions to the characterization of vibrational effects on the non-linear optical properties of molecules are suggested.

Original languageEnglish
Pages (from-to)247-255
Number of pages9
JournalJournal of Molecular Structure: THEOCHEM
Volume633
Issue number2-3
DOIs
Publication statusPublished - Aug 29 2003

Keywords

  • Ab initio
  • Anharmonic
  • Auto-correlation functions
  • Direct molecular dynamics
  • Harmonic
  • Infrared and Raman spectrum

ASJC Scopus subject areas

  • Biochemistry
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

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