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Zero point energy leakage in condensed phase dynamics: An assessment of quantum simulation methods for liquid water
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Habershon, Scott and Manolopoulos, D. E. (2009) Zero point energy leakage in condensed phase dynamics: An assessment of quantum simulation methods for liquid water. Journal of Chemical Physics, Vol. 131 (No. 24). p. 244518. doi:10.1063/1.3276109 ISSN 1089-7690.
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Official URL: http://dx.doi.org/10.1063/1.3276109
Abstract
The approximate quantum mechanical ring polymer molecular dynamics (RPMD) and linearized semiclassical initial value representation (LSC-IVR) methods are compared and contrasted in a study of the dynamics of the flexible q-TIP4P/F water model at room temperature. For this water model, a RPMD simulation gives a diffusion coefficient that is only a few percent larger than the classical diffusion coefficient, whereas a LSC-IVR simulation gives a diffusion coefficient that is three times larger. We attribute this discrepancy to the unphysical leakage of initially quantized zero point energy (ZPE) from the intramolecular to the intermolecular modes of the liquid as the LSC-IVR simulation progresses. In spite of this problem, which is avoided by construction in RPMD, the LSC-IVR may still provide a useful approximation to certain short-time dynamical properties which are not so strongly affected by the ZPE leakage. We illustrate this with an application to the liquid water dipole absorption spectrum, for which the RPMD approximation breaks down at frequencies in the O-H stretching region owing to contamination from the internal modes of the ring polymer. The LSC-IVR does not suffer from this difficulty and it appears to provide quite a promising way to calculate condensed phase vibrational spectra.
Item Type: | Journal Article | ||||
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Divisions: | Faculty of Science, Engineering and Medicine > Science > Chemistry | ||||
Journal or Publication Title: | Journal of Chemical Physics | ||||
Publisher: | American Institute of Physics | ||||
ISSN: | 1089-7690 | ||||
Official Date: | December 2009 | ||||
Dates: |
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Volume: | Vol. 131 | ||||
Number: | No. 24 | ||||
Page Range: | p. 244518 | ||||
DOI: | 10.1063/1.3276109 | ||||
Status: | Peer Reviewed | ||||
Publication Status: | Published | ||||
Access rights to Published version: | Restricted or Subscription Access |
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