MOLECULAR-DYNAMICS SIMULATION OF FAR-INFRARED ABSORPTION IN LIQUID OCS

The line shapes of the far infrared absorption spectra of liquid carbo nyl sulfide were calculated by molecular dynamics simulation at the th ermodynamic state of 298 K and a molar volume of 61.70 cm3/mol. The co rresponding time correlation functions of the system dipole moment wer e separated into contributions arising from the permanent molecular di poles and from the interaction-induced dipole moments evaluated from a first-order multipole-induced dipole scheme considering the electrost atic multipoles up to the octupole moment. We conclude that the far in frared absorption spectrum of liquid carbonyl sulfide is strongly domi nated by the orientational spectrum of the permanent dipoles at lower wavenumbers and, in addition, by the correlation of octupole-induced d ipoles at high frequencies.