Accurate vibrational spectra with TRPMD

Develop improved thermostatted ring polymer molecular dynamics (TRPMD) methodologies or thermostat parametrizations that yield quantitatively accurate vibrational spectra across frequency ranges and temperatures, eliminating spurious resonances and artificial broadening while preserving correct quantum features of high‑frequency modes in condensed‑phase systems.

Background

The text reviews how RPMD and CMD each exhibit characteristic failures for high‑frequency vibrational spectra (RPMD produces spurious resonances; CMD exhibits a curvature problem leading to red shifts). Thermostatted RPMD (TRPMD) damps internal ring‑polymer modes to mitigate resonances without altering centroid dynamics.

However, while TRPMD improves upon RPMD and CMD, the authors note that it still introduces line‑broadening, especially at lower temperatures, and that a fully satisfactory, generally accurate treatment of vibrational spectra using TRPMD has not yet been achieved.

References

But it is probably fair to say that the problem of computing accurate vibrational spectra with TRPMD has still not entirely been solved.

— Path Integral Methods in Atomistic Modelling: An Introduction  (2603.28588 - Ceriotti et al., 30 Mar 2026) in Section "An aside on thermostatted RPMD," Chapter "Ring polymer molecular dynamics"