A quantitative assessment of the accuracy of centroid molecular dynamicsfor the calculation of the infrared spectrum of liquid water

摘要

A detailed analysis of the infrared lineshapes corresponding to the intramolecular bond vibrations of HOD in either H20 or D20 is presented here in order to quantitatively assess the accuracy ofcentroid molecular dynamics in reproducing the correct features of the infrared spectrum of waterat ambient conditions. Through a direct comparison with the results obtained from mixed quantum-classical calculations, it is shown that centroid molecular dynamics provides accuratevibrational shifts and lineshapes when the intramolecular bond stretching vibrations are describedby a physically reasonable anharmonic potential. Artificially large redshifts due to a so-called"curvature problem" are instead obtained with an unphysical shifted harmonic potential because thelatter allows substantial probability density at zero bond lengths