Energies of the first row atoms from quantum Monte Carlo

Brown, M. D.; Trail, J. R.; Ríos, Pablo López; Needs, R. J.

doi:10.1063/1.2743972

Cited by 89 publications

(99 citation statements)

References 39 publications

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“…We tested optimization of the single-particle orbitals for N, O and F, but found this to have a negligible effect, in agreement with previous atomic studies 15,16 .…”

Section: Optimizationsupporting

confidence: 85%

“…13 and 14, our current implementation is more effective and robust. For example, Brown et al 15 were unable to lower the VMC energy of Ne using a multi-determinant expansion, which was easily achieved in the present study. The present optimization strategy is significantly different as we use MAD minimization to first optimize the non-linear parameters at each stage.…”

Section: A Atomic and Ionic Energiesmentioning

confidence: 65%

“…The present optimization strategy is significantly different as we use MAD minimization to first optimize the non-linear parameters at each stage. Brown et al 15 used a Jastrow factor based on an expansion in r, while we have used an expansion in powers of r/(r β + α). We have also employed a larger number of CSFs.…”

Section: A Atomic and Ionic Energiesmentioning

confidence: 99%

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Quantum Monte Carlo study of the first-row atoms and ions

Seth

Ríos²,

Needs³

2011

The Journal of Chemical Physics

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Quantum Monte Carlo calculations of the first-row atoms Li-Ne and their singlypositively-charged ions are reported. Multi-determinant-Jastrow-backflow trial wave functions are used which recover more than 98% of the correlation energy at the Variational Monte Carlo (VMC) level and more than 99% of the correlation energy at the Diffusion Monte Carlo (DMC) level for both the atoms and ions. We obtain the first ionization potentials to chemical accuracy. We also report scalar relativistic corrections to the energies, mass-polarization terms, and one-and two-electron expectation values.

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“…We tested optimization of the single-particle orbitals for N, O and F, but found this to have a negligible effect, in agreement with previous atomic studies 15,16 .…”

Section: Optimizationsupporting

confidence: 85%

Section: A Atomic and Ionic Energiesmentioning

confidence: 65%

See 1 more Smart Citation

Quantum Monte Carlo study of the first-row atoms and ions

Seth

Ríos²,

Needs³

2011

The Journal of Chemical Physics

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“…These observations let to further studies of backflow combined with the wave functions that have the minimal number of nodal cells -an important topological property associated with ground state wave functions. 36,37,38,39 One of the successes of this scheme are the very recent results of Brown et al 53 obtained from backflow correlated CI-Jastrow wave functions applied to first row all-electron atoms. In this study, we further test the limits of the backflow correlations to decrease the fixed node errors of the CI-Jastrow wave functions and, for the first time, also include backflow into the pfaffian-Jastrow pairing wave functions.…”

Section: B Carbon Atom and Dimermentioning

confidence: 99%

Pfaffian pairing and backflow wavefunctions for electronic structure quantum Monte Carlo methods

et al. 2008

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We investigate pfaffian trial wave functions with singlet and triplet pair orbitals by quantum Monte Carlo methods. We present mathematical identities and the key algebraic properties necessary for efficient evaluation of pfaffians. Following upon our previous study, 1 we explore the possibilities of expanding the wave function in linear combinations of pfaffians. We observe that molecular systems require much larger expansions than atomic systems and linear combinations of a few pfaffians lead to rather small gains in correlation energy. We also test the wave function based on fully-antisymmetrized product of independent pair orbitals. Despite its seemingly large variational potential, we do not observe additional gains in correlation energy. We find that pfaffians lead to substantial improvements in fermion nodes when compared to Hartree-Fock wave functions and exhibit the minimal number of two nodal domains in agreement with recent results on fermion nodes topology. We analyze the nodal structure differences of Hartree-Fock, pfaffian and essentially exact large-scale configuration interaction wave functions. Finally, we combine the recently proposed form of backflow correlations 2,3 with both determinantal and pfaffian based wave functions.

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“…In this work, we will show that quantum Monte Carlo (QMC) is an alternative efficient approach to achieve or surpass such accuracy in benzene crystals, as we previously demonstrated for the benzene dimer. 16 Quantum Monte Carlo (QMC), which approximately solves the electronic Schrödinger equation stochastically, 17 can yield highly accurate energies for atoms, 18,19 molecules, [20][21][22] and crystals. [23][24][25] Previous studies have shown that diffusion quantum Monte Carlo (DMC) can provide accurate energies for noncovalent interactions systems.…”

Section: Introductionmentioning

confidence: 99%

Low-pressure phase diagram of crystalline benzene from quantum Monte Carlo

Azadi

Cohen

2016

The Journal of Chemical Physics

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We studied the low-pressure (0–10 GPa) phase diagram of crystalline benzene using quantum Monte Carlo and density functional theory (DFT) methods. We performed diffusion quantum Monte Carlo (DMC) calculations to obtain accurate static phase diagrams as benchmarks for modern van der Waals density functionals. Using density functional perturbation theory, we computed the phonon contributions to the free energies. Our DFT enthalpy-pressure phase diagrams indicate that the Pbca and P21/c structures are the most stable phases within the studied pressure range. The DMC Gibbs free-energy calculations predict that the room temperature Pbca to P21/c phase transition occurs at 2.1(1) GPa. This prediction is consistent with available experimental results at room temperature. Our DMC calculations give 50.6 ± 0.5 kJ/mol for crystalline benzene lattice energy

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Energies of the first row atoms from quantum Monte Carlo

Cited by 89 publications

References 39 publications

Quantum Monte Carlo study of the first-row atoms and ions

Quantum Monte Carlo study of the first-row atoms and ions

Pfaffian pairing and backflow wavefunctions for electronic structure quantum Monte Carlo methods

Low-pressure phase diagram of crystalline benzene from quantum Monte Carlo

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