Communications: On artificial frequency shifts in infrared spectra obtained from centroid molecular dynamics: Quantum liquid water

Ivanov, Sergei D.; Witt, Alexander; Shiga, Motoyuki; Marx, Dominik

doi:10.1063/1.3290958

Cited by 73 publications

(91 citation statements)

References 27 publications

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“…These numbers of beads are typical for reaching convergence for ground-state properties of water at ambient conditions. 60,66 It is natural to expect the same convergence behavior, when the shift between PESs is relatively small.…”

Section: A Common Weighting Functionsmentioning

confidence: 99%

Quasi-classical approaches to vibronic spectra revisited

Karsten

Ivanov

Bokarev

et al. 2018

The Journal of Chemical Physics

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The framework to approach quasi-classical dynamics in the electronic ground state is well established and is based on the Kubo-transformed time correlation function (TCF), being the most classical-like quantum TCF. Here we discuss whether the choice of the Kubo-transformed TCF as a starting point for simulating vibronic spectra is as unambiguous as it is for vibrational ones. A generalized quantum TCF is proposed that contains many of the well-established TCFs as particular cases. It provides a framework to develop numerical protocols for simulating vibronic spectra via quasi-classical trajectory-based methods that allow for dynamics on many potential energy surfaces and nuclear quantum effects. The performance of the methods based on the well-known TCFs is investigated on 1D anharmonic model systems at finite temperatures. The flexibility inherent to the formulation of the generalized TCF provides a route to construct new TCFs that may lead to better numerical protocols as is shown on the same models.

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Section: A Common Weighting Functionsmentioning

confidence: 99%

Quasi-classical approaches to vibronic spectra revisited

Karsten

Ivanov

Bokarev

et al. 2018

The Journal of Chemical Physics

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“…However, both methods have been shown to exhibit serious artifacts when used to compute properties that are related to non-linear operators and high-frequency vibrations (228)(229)(230)(231)(232)(233)(234)(235). The latter problem can be mitigated by attaching thermostats to the internal modes of the ring polymer, a technique that can be seen as being half-way between RPMD and CMD (236).…”

Section: Simulating Quantum Dynamical Propertiesmentioning

confidence: 99%

Nuclear Quantum Effects in Water and Aqueous Systems: Experiment, Theory, and Current Challenges

et al. 2016

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Nuclear quantum effects influence the structure and dynamics of hydrogen bonded systems, such as water, which impacts their observed properties with widely varying magnitudes. This review highlights the recent significant developments in the experiment, theory and simulation of nuclear quantum effects in water. Novel experimental techniques, such as deep inelastic neutron scattering, now provide a detailed view of the role of nuclear quantum effects in water's 2 properties. These have been combined with theoretical developments such as the introduction of the competing quantum effects principle that allows the subtle interplay of water's quantum effects and their manifestation in experimental observables to be explained. We discuss how this principle has recently been used to explain the apparent dichotomy in water's isotope effects, which can range from very large to almost nonexistent depending on the property and conditions. We then review the latest major developments in simulation algorithms and theory that have enabled the efficient inclusion of nuclear quantum effects in molecular simulations, permitting their combination with on-the-fly evaluation of the potential energy surface using electronic structure theory. Finally, we identify current challenges and future opportunities in the area.3

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“…However, CMD can also give unphysical vibrational spectra, for a different reason known as the curvature problem. 42,43 This problem is again inherently multidimensional and is expected to arise whenever a high frequency stretching coordinate is combined with an angular coordinate, such as a rotational or a torsional degree of freedom. At low temperatures, the ring polymer spreads out around the angular coordinate, resulting in a softening of the centroid potential of mean force along the stretch.…”

Section: Centroid Molecular Dynamicsmentioning

confidence: 99%

How to remove the spurious resonances from ring polymer molecular dynamics

Rossi

Ceriotti

Manolopoulos

2014

The Journal of Chemical Physics

238

347

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Two of the most successful methods that are presently available for simulating the quantum dynamics of condensed phase systems are centroid molecular dynamics (CMD) and ring polymer molecular dynamics (RPMD). Despite their conceptual differences, practical implementations of these methods differ in just two respects: the choice of the Parrinello-Rahman mass matrix and whether or not a thermostat is applied to the internal modes of the ring polymer during the dynamics. Here we explore a method which is halfway between the two approximations: we keep the path integral bead masses equal to the physical particle masses but attach a Langevin thermostat to the internal modes of the ring polymer during the dynamics. We justify this by showing analytically that the inclusion of an internal mode thermostat does not affect any of the desirable features of RPMD: thermostatted RPMD (TRPMD) is equally valid with respect to everything that has actually been proven about the method as RPMD itself. In particular, because of the choice of bead masses, the resulting method is still optimum in the short-time limit, and the transition state approximation to its reaction rate theory remains closely related to the semiclassical instanton approximation in the deep quantum tunneling regime. In effect, there is a continuous family of methods with these properties, parameterised by the strength of the Langevin friction. Here we explore numerically how the approximation to quantum dynamics depends on this friction, with a particular emphasis on vibrational spectroscopy. We find that a broad range of frictions approaching optimal damping give similar results, and that these results are immune to both the resonance problem of RPMD and the curvature problem of CMD.

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Communications: On artificial frequency shifts in infrared spectra obtained from centroid molecular dynamics: Quantum liquid water

Cited by 73 publications

References 27 publications

Quasi-classical approaches to vibronic spectra revisited

Quasi-classical approaches to vibronic spectra revisited

Nuclear Quantum Effects in Water and Aqueous Systems: Experiment, Theory, and Current Challenges

How to remove the spurious resonances from ring polymer molecular dynamics

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