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Testing the quasicentroid molecular dynamics method on gas-phase ammonia.

Accepted version
Peer-reviewed

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Authors

Haggard, Christopher  ORCID logo  https://orcid.org/0000-0003-4228-1018
Sadhasivam, Vijay Ganesh 
Trenins, George 
Althorpe, Stuart C 

Abstract

Quasicentroid molecular dynamics (QCMD) is a path-integral method for approximating nuclear quantum effects in dynamics simulations, which has given promising results for gas- and condensed-phase water. In this work, by simulating the infrared spectrum of gas-phase ammonia, we test the feasibility of extending QCMD beyond water. Overall, QCMD works as well for ammonia as for water, reducing or eliminating blue shifts from the classical spectrum without introducing the artificial red shifts or broadening associated with other imaginary-time path-integral methods. However, QCMD gives only a modest improvement over the classical spectrum for the position of the symmetric bend mode, which is highly anharmonic (since it correlates with the inversion pathway). We expect QCMD to have similar problems with large-amplitude degrees of freedom in other molecules but otherwise to work as well as for water.

Description

Keywords

physics.chem-ph, physics.chem-ph

Journal Title

J Chem Phys

Conference Name

Journal ISSN

0021-9606
1089-7690

Volume Title

155

Publisher

AIP Publishing
Sponsorship
Engineering and Physical Sciences Research Council (EP/L015552/1)