Accurate molecular dynamics and nuclear quantum effects at low cost by multiple steps in real and imaginary time: Using density functional theory to accelerate wavefunction methods

Kapil, Venkat; VandeVondele, Joost; Ceriotti, Michele

doi:10.1063/1.4941091

Cited by 72 publications

(78 citation statements)

References 50 publications

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“…Because NQE are generally larger in H 2 O than in D 2 O hydrogen bonds, the former are weakened most by quantum fluctuations. This leads to the surprising conclusion the static‐electronically weaker hydrogen‐bond in D 2 O becomes stronger when NQE are taken into account, which is consistent with AI‐PIMD simulations of others . This effect is, however, weaker in bulk water than in the isolated water dimer.…”

Section: Discussionsupporting

confidence: 85%

Opposing Electronic and Nuclear Quantum Effects on Hydrogen Bonds in H₂O and D₂O

2019

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The effect of extending the OÀ H bond length(s) in water on the hydrogen-bonding strength has been investigated using static ab initio molecular orbital calculations. The "polar flattening" effect that causes a slight σ-hole to form on hydrogen atoms is strengthened when the bond is stretched, so that the σ-hole becomes more positive and hydrogen bonding stronger. In opposition to this electronic effect, path-integral ab initio molecular-dynamics simulations show that the nuclear quantum effect weakens the hydrogen bond in the water dimer. Thus, static electronic effects strengthen the hydrogen bond in H 2 O relative to D 2 O, whereas nuclear quantum effects weaken it. These quantum fluctuations are stronger for the water dimer than in bulk water.

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Section: Discussionsupporting

confidence: 85%

Opposing Electronic and Nuclear Quantum Effects on Hydrogen Bonds in H₂O and D₂O

2019

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“…al. [78]. It boils down to the the use of multiple time steps in real and imaginary time in which one uses a cheap reference potential which captures well the short ranged part of the potential.…”

Section: Discussionmentioning

confidence: 99%

Hydrogen dynamics in solid formic acid: insights from simulations with quantum colored-noise thermostats

Drużbicki

Krzystyniak

Hollas

et al. 2018

J. Phys.: Conf. Ser.

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Abstract. With an increase of computational capabilities, ab initio molecular dynamics becomes the natural choice for exploring the nuclear dynamics of solids. As based on classical mechanics, the validity of this approach is, in-principle, limited to the high-T regime, whilst low-temperature simulations require inclusion of quantum effects. The methods commonly used to account for nuclear quantum effects are based on the path-integral formalism, which become, however, particularly time consuming when high accuracy methods are used for calculating forces. Recently, new efficient alternative approaches to account for quantum nature of nuclei have been proposed, using so-called quantum thermostats. In this work, we examine the simulations performed with the quantum colored-noise thermostat introduced by Ceriotti [Phys. Rev. Lett., 103:030603, 2009]. We present the tests of portable implementation of the quantum thermostat in the ABIN program, which has been extended to periodic systems through the interface to CASTEP, a leading spectroscopy-oriented plane-wave density functional theory code. The range of applicability of quantum-thermostatted molecular dynamics simulations for the interpretation of neutron scattering data was examined and compared to classical molecular dynamics and lattice-dynamics simulations, using solid formic acid case as a test bed. We find that the approach is particularly useful for the modeling of low-temperature inelastic neutron scattering spectra as well as provides some theoretical estimate for the low-limit of the mean kinetic energy. While finding the quantum-thermostat to seriously affect the dynamic properties of the title system, we illustrate to which extent the unperturbed response can be successfully recovered. IntroductionMolecular dynamics (MD) has evolved into a powerful numerical method to investigate structural and dynamical properties of condensed matter [1]. For an atom, these calculations are, however, only valid in the classical limit, i.e. for temperatures safely above the Debye temperature that signals the onset of quantum effects. The Debye temperature is often of the order of few hundred Kelvins and nuclear quantum effects (NQEs) are thus indeed important over a wide range of temperatures [2,3].Quantum fluctuations stemming from the Heisenberg uncertainty principle make the energy of a particle at 0 K higher than a the potential energy minimum, leading to a concept of zero point energy (ZPE) (see Fig. 1). While ZPE reflects the quantum nature of atomic motion, it can be approximately accounted for by lattice-dynamics calculations, which, by definition, are based on the quantum harmonic oscillator model.

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“…Owing to the need to separate the time-scales present in the potential energy, the application of RPC to ab initio PIMD simulations has provided more of a challenge. However, recent work has shown that RPC can be used to dramatically accelerate both DFT(139) and MP2 (197) calculations, while retaining chemical reactivity, by using a reference potential to create a smooth difference force which can then be evaluated on the contracted ring polymer.…”

Section: Ring Polymermentioning

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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Accurate molecular dynamics and nuclear quantum effects at low cost by multiple steps in real and imaginary time: Using density functional theory to accelerate wavefunction methods

Cited by 72 publications

References 50 publications

Opposing Electronic and Nuclear Quantum Effects on Hydrogen Bonds in H₂O and D₂O

Opposing Electronic and Nuclear Quantum Effects on Hydrogen Bonds in H₂O and D₂O

Hydrogen dynamics in solid formic acid: insights from simulations with quantum colored-noise thermostats

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

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Accurate molecular dynamics and nuclear quantum effects at low cost by multiple steps in real and imaginary time: Using density functional theory to accelerate wavefunction methods

Cited by 72 publications

References 50 publications

Opposing Electronic and Nuclear Quantum Effects on Hydrogen Bonds in H2O and D2O

Opposing Electronic and Nuclear Quantum Effects on Hydrogen Bonds in H2O and D2O

Hydrogen dynamics in solid formic acid: insights from simulations with quantum colored-noise thermostats

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

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Product

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Opposing Electronic and Nuclear Quantum Effects on Hydrogen Bonds in H₂O and D₂O

Opposing Electronic and Nuclear Quantum Effects on Hydrogen Bonds in H₂O and D₂O