MoRiBS-PIMC: A program to simulate molecular rotors in bosonic solvents using path-integral Monte Carlo

Zeng, Tao; Blinov, N. S.; Guillon, Grégoire; Li, Hui; Bishop, Kevin P.; Roy, Pierre‐Nicholas

doi:10.1016/j.cpc.2016.02.025

Cited by 11 publications

(6 citation statements)

References 54 publications

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“…S5). Indeed, at very low temperature, special symmetry adapted sampling should be applied to distinguish the nuclear spin species along with thousands of beads, as done by Roy and coworkers in path integral Monte Carlo (PIMC) simulations for obtaining superfluid density and related properties at a few Kelvin 43 .…”

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“…Indeed, at very low temperature, special symmetry adapted sampling should be applied to distinguish the nuclear spin species along with thousands of beads, as done by Roy and coworkers in path integral Monte Carlo (PIMC) simulations for obtaining superfluid density and related properties at a few kelvin. 43 In this work, we choose to sample both molecules at a fixed gas temperature (T g = 300 K) on a rigid surface for simplicity. Therefore, only the ZPE of the molecule is incorporated in the RPMD simulations.…”

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confidence: 99%

“…In Figure , the PIMD internal energies computed via the centroid virial theorem in both molecules are found to gradually increase with the number of beads and converge to QIEs (without nuclear spin statistics) with P = 40 for H 2 and P = 30 for D 2 O at T g > 200 K. The convergence becomes increasingly more difficult as T g decreases (see more clearly in Figure S5). Indeed, at very low temperature, special symmetry adapted sampling should be applied to distinguish the nuclear spin species along with thousands of beads, as done by Roy and co-workers in path integral Monte Carlo (PIMC) simulations for obtaining superfluid density and related properties at a few kelvin …”

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Ring Polymer Molecular Dynamics in Gas–Surface Reactions: Inclusion of Quantum Effects Made Simple

Liu

Zhang

et al. 2019

J. Phys. Chem. Lett.

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Accurately modeling gas-surface collision dynamics presents a great challenge for theory, especially in the low energy (or temperature) regime where quantum effects are important. Here, a path integral based non-equilibrium ring polymer molecular dynamics (NE-RPMD) approach is adapted to calculate dissociative initial sticking probabilities (S0) of H2 on Cu(111) and D2O on Ni(111), revealing distinct quantum nature in the two benchmark surface reactions. NE-RPMD successfully captures quantum tunneling in H2 dissociation at very low energies, where the quasi-classical trajectory (QCT) method suddenly fails. Additionally, QCT substantially overestimates S0 of D2O due to severe zero point energy (ZPE) leakage, even at collision energies higher than the ZPE-corrected barrier. Instead, NE-RPMD predicts S0 values of D2O in much improved agreement with reference results obtained by the quantum wavepacket method with reasonable corrections of the thermal contribution. Our results suggest NE-RPMD as a promising approach to model quantum effects in gas-surface reactions. TOC graphic3 Dissociative adsorption of small molecules at surfaces is the initial and often rate-limiting step in many interfacial processes such as heterogeneous catalysis and corrosion. Initial sticking probability (S0) is an important observable to reveal the adsorption mechanism and dynamics at solid surfaces, which can be now precisely measured as a function of incidence energy by molecular beam experiments 1-2 . S0 can be 10 -5 or even lower at low energies in many highly activated systems, e.g. methane and water dissociative chemisorption on metal surfaces 1, 3 , representing indispensable steps in methane steaming reforming. Given the large number of degrees of freedom (DOFs), however, it is very challenging to accurately predict S0 from first-principles calculations.Ideally, given an accurate global potential energy surface (PES), exact quantum initial sticking probabilities can be extracted by fully-coupled quantum dynamical (QD) methods, including both time-dependent 4-6 and time-independent 7 implementations. While such molecule-surface PESs can be now routinely developed 8-9 , high-dimensional QD calculations remain extremely difficult and are limited to involve at most nine molecular DOFs so far 10 , due to their poor scaling with dimensionality. Alternatively, the quasiclassical trajectory (QCT) method is much more efficient to model surface reaction dynamics and visualize the associated mechanism 4 . In QCT calculations, the zero point energy (ZPE) of the reactant is approximately included, while the atomic motion is evolved classically. Such QCT applications in H2 activated dissociation on various metal surfaces do reproduce the QD calculated S0 values above the ZPE-corrected barrier quite well 4, 11 .When explicit PESs are unavailable, ab initial molecular dynamics (AIMD) simulations, in which the energies and forces are calculated on-the-fly, have also been performed to study surface reactions 12 . Although AIMD is computationally expen...

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Ring Polymer Molecular Dynamics in Gas–Surface Reactions: Inclusion of Quantum Effects Made Simple

Liu

Zhang

et al. 2019

J. Phys. Chem. Lett.

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“…We have implemented the sampling ensembles and estimators in our in-house software, MoRiBS-PIMC, a program to simulate molecular rotors in bosonic solvents using path-integral Monte Carlo. 29 We refer the reader to Refs. 29 and 30 for further details regarding the simulation of molecular rotors in quantum environments.…”

Section: Numerical Resultsmentioning

confidence: 99%

A path integral ground state replica trick approach for the computation of entanglement entropy of dipolar linear rotors

Sahoo

Iouchtchenko

Herdman

et al. 2020

The Journal of Chemical Physics

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We calculate the second Rényi entanglement entropy for systems of interacting linear rotors in their ground state as a measure of entanglement for continuous rotational degrees of freedom. The entropy is defined in relation to the purity of a subsystem in a bipartite quantum system, and to compute it, we compare two sampling ensembles based on the path integral ground state (PIGS) formalism. This scheme centers on the replica trick and is aided by the ratio trick, both developed in this context by Hastings et al. [Phys. Rev. Lett. 104, 157201 (2010)]. We study a system composed of linear quantum rotors on a lattice in one dimension, interacting via an anisotropic dipole-dipole potential. The ground state second Rényi entropies estimated by PIGS are benchmarked against those from the density matrix renormalization group for various interaction strengths and system sizes. We find that the entropy grows with an increase in interaction strength, and for large enough systems, it appears to plateau near log(2). We posit that the limiting case of many strongly interacting rotors behaves akin to a lattice of two-level particles in a cat state, in which one naturally finds an entanglement entropy of log(2).

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“…We chose here to study a CO 2 dopant as it is valence isoelectronic to OCS and a higher superfluid response is expected due to the less anisotropic interactions with the bosonic solvents [see Supplemental Material (SM) for details [26] A PIMC algorithm for the sampling of exchanges for two sets of identical bosonic particles, namely 4 He and p-H 2 , has been developed. Other details of the PIMC approach have been described elsewhere [10,[34][35][36][37]. Simulation details are provided in the SM [26].…”

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Suppression of Parahydrogen Superfluidity in a Doped Nanoscale Bose Fluid Mixture

Zhang

Zeng

et al. 2019

Phys. Rev. Lett.

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MoRiBS-PIMC: A program to simulate molecular rotors in bosonic solvents using path-integral Monte Carlo

Cited by 11 publications

References 54 publications

Ring Polymer Molecular Dynamics in Gas–Surface Reactions: Inclusion of Quantum Effects Made Simple

Ring Polymer Molecular Dynamics in Gas–Surface Reactions: Inclusion of Quantum Effects Made Simple

A path integral ground state replica trick approach for the computation of entanglement entropy of dipolar linear rotors

Suppression of Parahydrogen Superfluidity in a Doped Nanoscale Bose Fluid Mixture

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