Efficient Computation of Difference Vibrational Spectra in Isothermal-Isobaric Ensemble

Tatsuya Joutsuka, Akihiro Morita

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


Difference spectroscopy between two close systems is widely used to augment its selectivity to the different parts of the observed system, though the molecular dynamics calculation of tiny difference spectra would be computationally extraordinary demanding by subtraction of two spectra. Therefore, we have proposed an efficient computational algorithm of difference spectra without resorting to the subtraction. The present paper reports our extension of the theoretical method in the isothermal-isobaric (NPT) ensemble. The present theory expands our applications of analysis including pressure dependence of the spectra. We verified that the present theory yields accurate difference spectra in the NPT condition as well, with remarkable computational efficiency over the straightforward subtraction by several orders of magnitude. This method is further applied to vibrational spectra of liquid water with varying pressure and succeeded in reproducing tiny difference spectra by pressure change. The anomalous pressure dependence is elucidated in relation to other properties of liquid water.

Original languageEnglish
Pages (from-to)11229-11238
Number of pages10
JournalJournal of Physical Chemistry B
Issue number43
Publication statusPublished - 2016 Nov 3


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