Fixed-node diffusion Monte Carlo method for lithium systems

Rasch, Kevin; Mitáš, Luboš

doi:10.1103/physrevb.92.045122

Cited by 14 publications

(9 citation statements)

References 66 publications

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“…Further, finite system size has only a small effect on the electronic structure factor, because the δS(k) of the 54-atom simulation is very close to the 432-atom one. All pseudopotential δS(k) can be accurately described by the RPA S(k) at the same valence density when k < 0.4 a.u.. Our all-electron structure factor agrees well with that from the previous QMC study [4].…”

Section: Qmc Electronic Structure Factorsupporting

confidence: 87%

“…The mixed-estimator errors are larger than their pseudopotential counterparts. Nevertheless, our DMC total energy of -2.5152 ha/e is 2.3 mha/e lower than the -2.5129 ha/e obtained in a previous QMC study using localized basis and the PBE functional [4]. The previous study was performed at a valence density of r s = 3.24, which is close to our r s = 3.25.…”

Section: Qmc Energiessupporting

confidence: 70%

“…Since the pioneering work of Eisenberger et al 1,2 , Compton scattering experiments have been performed on simple metals such as Li [3][4][5][6][7] , Be 8,9 , Na 10 as well as more complicated materials. Accompanying the scattering experiments are numerous theoretical calculations using different electronic structure theories including density functional theory (DFT) 3,4,7,[11][12][13][14][15][16] , QMC 10,17 , and GW [18][19][20][21] . The Compton profiles in ref.…”

Section: Introductionmentioning

confidence: 99%

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Quantum Monte Carlo Compton profiles of solid and liquid lithium

et al. 2020

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We computed the Compton profile of solid and liquid lithium using quantum Monte Carlo (QMC) and compared with recent experimental measurements obtaining good agreement. Importantly, we find it crucial to account for proper core-valence orthogonalization and to address density differences when comparing with experiment. To account for disorder effects, we sampled finite-temperature configurations using molecular dynamics (MD), then performed diffusion Monte Carlo (DMC) simulations on each configuration. We used Slater-Jastrow wavefunctions and grand-canonical twistaveraged boundary conditions. A QMC pseudopotential correction, derived from an all-electron DMC simulation of the perfect crystal was also used. Our calculations provide the first all-electron QMC benchmark for the Compton profile of lithium crystal and pseudopotential-corrected QMC Compton profiles for both the liquid and solid. arXiv:1912.12295v1 [cond-mat.mtrl-sci]

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Section: Qmc Electronic Structure Factorsupporting

confidence: 87%

Section: Qmc Energiessupporting

confidence: 70%

Section: Introductionmentioning

confidence: 99%

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Quantum Monte Carlo Compton profiles of solid and liquid lithium

et al. 2020

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“…Bulk Li has been the subject of intense studies due to the emergence of exotic quantum states, including superconductivity 55,56 , in its phase diagram under pressure and also to its extensive application in battery development. Previous QMC investigations 57,58 provided very accurate results and, at the same time, they established the important role of FS effects in determining the converged ground state energy 58,59 . For treating this system the localized basis set used in this work is [J]2s2p [D]4s4p and the 1s core electron is replaced with a BFD pseudopotential 40 .…”

Section: Total Energymentioning

confidence: 99%

Exact special twist method for quantum Monte Carlo simulations

et al. 2016

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We present a systematic investigation of the special twist method introduced by Rajagopal et al. [Phys. Rev. B 51, 10591 (1995)] for reducing finite-size effects in correlated calculations of periodic extended systems with Coulomb interactions and Fermi statistics. We propose a procedure for finding special twist values which, at variance with previous applications of this method, reproduce the energy of the mean-field infinite-size limit solution within an adjustable (arbitrarily small) numerical error. This choice of the special twist is shown to be the most accurate single-twist solution for curing one-body finite-size effects in correlated calculations. For these reasons we dubbed our procedure "exact special twist" (EST). EST only needs a fully converged independent-particles or mean-field calculation within the primitive cell and a simple fit to find the special twist along a specific direction in the Brillouin zone. We first assess the performances of EST in a simple correlated model such as the 3D electron gas. Afterwards, we test its efficiency within ab initio quantum Monte Carlo simulations of metallic elements of increasing complexity. We show that EST displays an overall good performance in reducing finite-size errors comparable to the widely used twist average technique but at a much lower computational cost, since it involves the evaluation of just one wavefunction. We also demonstrate that the EST method shows similar performances in the calculation of correlation functions, such as the ionic forces for structural relaxation and the pair radial distribution function in liquid hydrogen. Our conclusions point to the usefulness of EST for correlated supercell calculations; our method will be particularly relevant when the physical problem under consideration requires large periodic cells.

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“…Those studies have provided a deep understanding of thermal dynamica behaviors in a small size system [1][2][3]. Cluster is considered as a transition state from molecular to bulk materials.…”

Section: Introductionmentioning

confidence: 99%

Melting and crystallization in large sized copper cluster

Cui

et al. 2016

Integrated Ferroelectrics

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The melting and crystallization with two different cooling rates of large sized Cu N (N = 1956, 2112, 2208, and 2340) nanoclusters are simulated by using molecular dynamics technique with the frame work of embedded atom method. The potential energy as a function of temperatures is obtained and the structural details are analyzed. The results reveal that the melting and freezing temperatures increase almost linearly with the atom number of the clusters slowly. All the copper nanoclusters have negative heat capacity around the phase transition temperature, and the clusters with slow cooling rates have icosahedral structure at 300 K.

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Fixed-node diffusion Monte Carlo method for lithium systems

Cited by 14 publications

References 66 publications

Quantum Monte Carlo Compton profiles of solid and liquid lithium

Quantum Monte Carlo Compton profiles of solid and liquid lithium

Exact special twist method for quantum Monte Carlo simulations

Melting and crystallization in large sized copper cluster

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