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

  title={Testing the quasicentroid molecular dynamics method on gas-phase ammonia.},
  author={Christopher Haggard and Vijay Ganesh Sadhasivam and George Trenins and Stuart C. Althorpe},
  journal={The Journal of chemical physics},
  volume={155 17},
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… 

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Fast quasi-centroid molecular dynamics
We describe a fast implementation of the quasi-centroid molecular dynamics (QCMD) method in which the quasi-centroid potential of mean force is approximated as a separable correction to the classical
Incorporating Nuclear Quantum Effects in Molecular Dynamics
The accurate incorporation of nuclear quantum effects in large-scale molecular dynamics simulations remains a significant challenge. Here, we develop a new formulation of the equations of motion for


Here we are referring to the LAM of the centroid from the quasicentroid, not the inversion pathway
Note that ρ defined here and the inversion coordinate ρ in ref. 30 are related as ρ = π 2 − ρ
Strictly, the quasicentroid constraint does not prevent the instanton geometry from forming
these fluctuations do not sufficiently carry over to the quasicentroid due to strong anharmonicity, so
  • QCMD