Numerical tests of a fixed vibrational basis/gaussian bath theory for small molecule dynamics in low-temperature media.

Academic Article


  • A recently framed quantum/semiclassical treatment for the internal nuclear dynamics of a small molecule and the induced small-amplitude coherent motion of a low-temperature host medium (Chapman, C. T.; Cina, J. A. J. Chem. Phys.2007,127, 114502) is further analyzed and subjected to initial tests of its numerical implementation. In the illustrative context of a 1D system interacting with a 1D medium, we rederive the fixed vibrational basis/gaussian bath (FVB/GB) equations of motion for the parameters defining the gaussian bath wave packet accompanying each of the energy eigenkets of the quantum mechanical system. The conditions of validity for the gaussian-bath approximation are shown to coincide with those supporting approximate population conservation. We perform initial numerical tests of the FVB/GB scheme and illustrate the semiclassical description it provides of coherent motion in the medium by comparing its predictions with the exact results for a high-frequency system harmonic oscillator bilinearly coupled to a lower-frequency bath oscillator. Linear vibronic absorption spectra or, equivalently, ultrafast wave packet interferometry signals are shown to be readily and accurately calculable within the FVB/GB framework.
  • Authors

  • Chapman, Craig
  • Cheng, Xiaolu
  • Cina, Jeffrey A
  • Status

    Publication Date

  • April 28, 2011
  • Published In


  • Quantum Theory
  • Temperature
  • Vibration
  • Digital Object Identifier (doi)

    Pubmed Id

  • 21462985
  • Start Page

  • 3980
  • End Page

  • 3989
  • Volume

  • 115
  • Issue

  • 16