Foreword

Sorella, S. P.; Cucchieri, Attilio; Mendes, Tereza

doi:10.1590/s0103-97332007000200001

Cited by 20 publications

(46 citation statements)

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“…We used a Jastrow-Slater variational wave function, with Slater and Jastrow parts developed on a localized Gaussian basis set. The Jastrow factor contains correlation terms up to the four-body (electron-ion-electron-ion) form, able to capture van der Waals effects within variational Monte Carlo (VMC) [22]. The wave function has been fully optimized (Slater orbitals together with Jastrow coefficients) by energy minimization [23], starting from DFT-LDA generated one-body orbitals.…”

Section: Methodsmentioning

confidence: 99%

van der Waals forces stabilize low-energy polymorphism in B2O3 : Implications for the crystallization anomaly

Ferlat

Hellgren

Coudert

et al. 2019

Phys. Rev. Materials

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The cohesive energies and structural properties of recently predicted -and never synthesized -B 2 O 3 polymorphs are investigated from first principles using density functional theory and high-accuracy many-body methods, namely, the random phase approximation and quantum Monte Carlo. We demonstrate that the van der Waals forces play a key role in making the experimentally known polymorph (B 2 O 3 -I) the lowest in energy, with many competing metastable structures lying only a few kcal/mol above. Remarkably, all metastable crystals are comparable in energy and density to the glass, while having anisotropic and mechanically soft structures. Furthermore, the best metastable polymorph according to our stability criteria has a structural motif found in both the glass and a recently synthesized borosulfate compound. Our findings provide new perspectives for understanding the B 2 O 3 anomalous behavior, namely, its propensity to vitrify in a glassy structure drastically different from the known crystal. arXiv:1906.10605v1 [cond-mat.mtrl-sci]

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Section: Methodsmentioning

confidence: 99%

van der Waals forces stabilize low-energy polymorphism in B2O3 : Implications for the crystallization anomaly

Ferlat

Hellgren

Coudert

et al. 2019

Phys. Rev. Materials

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“…Compared to a direct inclusion of orbital-dependent BF correlations through different coordinate transformations for different orbitals, the computational cost of our OBF wave function thus maintains the overall N 3 scaling of standard BF, with a small additional cost of less than a factor 2. The increased number of independent terms in each orbital can be dealt with by modern optimization techniques 16,17 .…”

Section: Case Study Of the First Row Atomsmentioning

confidence: 99%

“…All radial functions u, w, ξ 0 , and ξ 1 are expressed as LPQHI. The variational parameters (58 for Li and Be, 67 for the other atoms) are optimized by minimization of the variational energy 16 . The resulting VMC and DMC energies obtained are listed in Table I.…”

Section: Case Study Of the First Row Atomsmentioning

confidence: 99%

Orbital-dependent backflow wave functions for real-space quantum Monte Carlo

Holzmann

Moroni

2019

Phys. Rev. B

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We present and motivate an efficient way to include orbital dependent many-body correlations in trial wave function of real-space Quantum Monte Carlo methods for use in electronic structure calculations. We apply our new orbital-dependent backflow wave function to calculate ground state energies of the first row atoms using variational and diffusion Monte Carlo methods. The systematic overall gain of correlation energy with respect to single determinant Jastrow-Slater wave functions is competitive with the best single determinant trial wave functions currently available. The computational cost per Monte Carlo step is comparable to that of simple backflow calculations.

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“…The VMC results well reproduce the exact one even with the small number of N z N y . In order to improve the precision of the angularmomentum projection so that the expectation value of J 2 equals I(I + 1) exactly to 6 decimal digits, the necessary number of points is higher than the minimal one given by (N z , N y ) = (28,14), (28,14), (31,16), and (35, 18) for I π = 0 + , 2 + , 4 + , and 6 + states, respectively.…”

Section: Approximate Angular-momentum Projectionmentioning

confidence: 99%

“…where ǫ is a small constant. This modification makes the overlap matrix positive definite and stable even if S ij is calculated stochastically including a certain error [31]. In this work, we typically take ǫ = 0.01/ √ i where i is the number of iterations.…”

Section: Appendix C: Stochastic Reconfigurationmentioning

confidence: 99%

Variational Monte Carlo method for shell-model calculations in odd-mass nuclei and restoration of symmetry

Shimizu

Mizusaki

2018

Phys. Rev. C

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We investigate two kinds of extensions for the variational Monte Carlo (VMC) method with the Pfaffian in the nuclear shell-model calculations. One is the extension to odd-mass nuclei, for which we find a new Pfaffian expression of the VMC matrix elements. We can, thereby, give a unified VMC framework both for even and odd mass nuclei. The other is the extension of the variation after angular-momentum projection. We successfully implement the full angular-momentum projected trial state into the VMC method, which can provide us with the precise yrast energies. We also find a unique characteristic, namely that this angular-momentum projection in the VMC can be even "approximately" performed. This characteristic is useful not only for efficient computation but also for precise estimation of the yrast energies through the energy-variance extrapolation.

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Foreword

Cited by 20 publications

References 0 publications

van der Waals forces stabilize low-energy polymorphism in B2O3 : Implications for the crystallization anomaly

van der Waals forces stabilize low-energy polymorphism in B2O3 : Implications for the crystallization anomaly

Orbital-dependent backflow wave functions for real-space quantum Monte Carlo

Variational Monte Carlo method for shell-model calculations in odd-mass nuclei and restoration of symmetry

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