Testing the quasicentroid molecular dynamics method on gas-phase ammonia

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. Here, 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.

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Cited by in corpus (9)

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• Incorporating Nuclear Quantum Effects in Molecular Dynamics with a Constrained Minimized Energy Surface
• Fast quasi-centroid molecular dynamics
• Fast quasi-centroid molecular dynamics for water and ice
• Improved torque estimator for condensed-phase quasicentroid molecular dynamics
• Comparison of Matsubara dynamics with exact quantum dynamics for an oscillator coupled to a dissipative bath
• h-CMD: An efficient hybrid fast centroid and quasi-centroid molecular dynamics method for the simulation of vibrational spectra
• Semiclassical Dynamics in Wigner Phase Space I : Adiabatic Hybrid Wigner Dynamics