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We study three wave function optimization methods based on energy minimization in a variational Monte Carlo framework: the Newton, linear and perturbative methods. In the Newton method, the parameter variations are calculated from the…

Chemical Physics · Physics 2015-06-26 Julien Toulouse , C. J. Umrigar

We formulate the "tensor-optimized high-momentum antisymmetrized molecular dynamics (TO-HMAMD)" framework for ab initio calculations of nuclei by hybridizing the tensor-optimized (TO-) and high-momentum (HM-) AMD approaches. This hybrid…

Diradical molecules are essential species involved in many organic and inorganic chemical reactions. The computational study of their electronic structure is often challenging, because a reliable description of the correlation, and in…

Chemical Physics · Physics 2014-06-18 Andrea Zen , Emanuele Coccia , Ye Luo , Sandro Sorella , Leonardo Guidoni

We show that a simple correlated wave function, obtained by applying a Jastrow correlation term to an Antisymmetrized Geminal Power (AGP), based upon singlet pairs between electrons, is particularly suited for describing the electronic…

Other Condensed Matter · Physics 2009-11-10 M. Casula , C. Attaccalite , S. Sorella

As a new scheme of treating the tensor interaction of the nucleon-nucleon interaction, there is a proposal of a tensor-optimized shell-model (TOSM) for the study of medium and heavy nuclei. The TOSM includes the deuteron-like tensor…

Nuclear Theory · Physics 2012-07-03 Kaori Horii , Hiroshi Toki , Takayuki Myo , Kiyomi Ikeda

We pursue the development and application of the recently-introduced linear optimization method for determining the optimal linear and nonlinear parameters of Jastrow-Slater wave functions in a variational Monte Carlo framework. In this…

Computational Physics · Physics 2008-05-02 Julien Toulouse , C. J. Umrigar

Torsional modes within a complex molecule containing various functional groups are often strongly coupled so that the harmonic approximation and one-dimensional torsional treatment are inaccurate to evaluate their partition functions. A…

Computational Physics · Physics 2020-08-07 Chengming He , Yicheng Chi , Peng Zhang

Herein, we report accurate atomization energy calculations for 55 molecules in the Gaussian-2 (G2) set using lattice regularized diffusion Monte Carlo (LRDMC). We compare the Jastrow-Slater determinant ansatz with a more flexible JsAGPs…

Chemical Physics · Physics 2023-04-19 Abhishek Raghav , Ryo Maezono , Kenta Hongo , Sandro Sorella , Kousuke Nakano

We investigate the optimization of flexible tailored real-space Jastrow factors for use in the transcorrelated (TC) method in combination with highly accurate quantum chemistry methods such as initiator full configuration interaction…

The extended Lagrangian molecular dynamics (XLMD) method provides a useful framework for reducing the computational cost of a class of molecular dynamics simulations with constrained latent variables. The XLMD method relaxes the constraints…

Numerical Analysis · Mathematics 2020-10-16 Dong An , Lin Lin , Michael Lindsey

We study the extension of our translationally invariant treatment of few-body nuclear systems to include tensor forces and correlations. It is shown that a direct application of our method is not as successful for realistic V6 interactions…

Nuclear Theory · Physics 2009-10-31 R. F. Bishop , R. Guardiola , I. Moliner , J. Navarro , M. Portesi , A. Puente , N. R. Walet

Extended Lagrangian molecular dynamics (XLMD) is a general method for performing molecular dynamics simulations using quantum and classical many-body potentials. Recently several new XLMD schemes have been proposed and tested on several…

Numerical Analysis · Mathematics 2020-02-28 Dong An , Sara Y. Cheng , Teresa Head-Gordon , Lin Lin , Jianfeng Lu

We apply the transcorrelated method to problems of multireference character. For this, we show that the choice of reference wavefunction during the Jastrow optimisation procedure is vital, and we propose a workflow wherein we use…

Variational wave functions based on a Margenau-Brink cluster model with short range and state dependent correlations, and angular momentum projection are obtained for some nuclei with $12 \leq A \leq 16$. The calculations have been carried…

Nuclear Theory · Physics 2009-11-10 E. Buendia , F. J. Galvez , A. Sarsa

To investigate $pn$ pair correlations in $N=Z=\textrm{odd}$ nuclei, we develop a new framework based on the generator coordinate method of the $\beta\gamma$ constraint antisymmetrized molecular dynamics. In the framework, the isospin…

Nuclear Theory · Physics 2017-02-10 Hiroyuki Morita , Yoshiko Kanada-En'yo

We push the boundaries of electronic structure-based \textit{ab-initio} molecular dynamics (AIMD) beyond 100 million atoms. This scale is otherwise barely reachable with classical force-field methods or novel neural network and machine…

Thermal quantum time-correlation functions are of fundamental importance in quantum dynamics, allowing experimentally-measurable properties such as reaction rates, diffusion constants and vibrational spectra to be computed from first…

Chemical Physics · Physics 2017-07-25 Timothy J. H. Hele

We present an accelerated ``on-the-fly'' coupled-cluster path-integral molecular dynamics (PIMD) method for finite-temperature simulations in which electron correlation and nuclear quantum effects are treated simultaneously. The approach is…

Chemical Physics · Physics 2026-05-20 Thomas Spura , Hossam Elgabarty , Thomas D. Kühne

We report a quantum Monte Carlo (QMC) study, on a very simple but nevertheless very instructive model system of four hydrogen atoms, recently proposed in Ref. 1. We find that the Jastrow correlated Antisymmetrized Geminal Power (JAGP) is…

Chemical Physics · Physics 2019-05-22 Claudio Genovese , Antonella Meninno , Sandro Sorella

In this article, we report a fully ab initio variational Monte Carlo study of the linear, and periodic chain of Hydrogen atoms, a prototype system providing the simplest example of strong electronic correlation in low dimensions. In…

Strongly Correlated Electrons · Physics 2015-05-30 Lorenzo Stella , Claudio Attaccalite , Sandro Sorella , Angel Rubio