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In our previous study, we proposed the low-rank antisymmetric product of geminals (APG) method, which reconstructs the wavefunction by extracting only the important eigenvalues from the APG wave function. However, its practical application…

Chemical Physics · Physics 2025-08-19 Airi Kawasaki , Rei Oshima , Naoki Nakatani , Hiromi Nakai

In this work, atomic calculations were performed within the local-density and generalized-gradient approximations of exchange and correlation density functionals within density-functional theory to provide accurate periodic trends of first…

Atomic Physics · Physics 2016-11-04 Mauro Ribeiro

The method of McCurdy, Baertschy, and Rescigno, J. Phys. B, 37, R137 (2004) is generalized to obtain a straightforward, surprisingly accurate, and scalable numerical representation for calculating the electronic wave functions of molecules.…

A precise discussion of a single bond requires consideration of two-particle wave function for the particles involved. Here we define and determine rigorously the intrinsic covalency and connected characteristics on the canonical example of…

Strongly Correlated Electrons · Physics 2022-11-01 Maciej Hendzel , Maciej Fidrysiak , Józef Spałek

An exterior complex scaling technique is applied to compute Stark resonance parameters for two molecular orbitals ($1b_{1}$ and $1b_{2}$) represented in the field-free limit in a single-center expansion. For electric DC field configurations…

Atomic Physics · Physics 2016-11-23 Susana Arias Laso , Marko Horbatsch

Molecular orbital theory is powerful both as a conceptual tool for understanding chemical bonding, and as a theoretical framework for ab initio quantum chemistry. Despite its undoubted success, MO theory has well documented shortcomings,…

Chemical Physics · Physics 2024-02-15 Daniel Marti-Dafcik , Nicholas Lee , Hugh G. A. Burton , David P. Tew

Atomic forces are calculated for first-row monohydrides and carbon monoxide within electronic quantum Monte Carlo (QMC). Accurate and efficient forces are achieved by using an improved method for moving variational parameters in variational…

Chemical Physics · Physics 2009-11-10 Myung Won Lee , Massimo Mella , Andrew M. Rappe

Variational wave function ansatze are an invaluable tool to study the properties of strongly correlated systems. We propose such a wave function, based on the theory of auxiliary fields and combining aspects of auxiliary-field quantum Monte…

Strongly Correlated Electrons · Physics 2024-03-13 Ryan Levy , Miguel A. Morales , Shiwei Zhang

We present a new, non-variational orbital-optimization scheme for the Antisymmetric Product of one-reference orbital Geminal wave function. Our approach is motivated by the observation that an orbital-optimized seniority-zero configuration…

The auxiliary functions provide efficient computation of integrals arising at the self-consistent field (SCF) level for molecules using Slater-type bases. This applies both in relativistic and non-relativistic electronic structure theory.…

Chemical Physics · Physics 2017-11-29 A. Bagci , P. E. Hoggan

Analytic first and second derivatives of the energy are developed for the fragment molecular orbital method interfaced with molecular mechanics in the electrostatic embedding scheme at the level of Hartree-Fock and density functional…

Chemical Physics · Physics 2020-05-19 Hiroya Nakata , Dmitri G. Fedorov

A method is developed that allows analysis of quantum Monte Carlo simulations to identify errors in trial wave functions. The purpose of this method is to allow for the systematic improvement of variational wave functions by identifying…

Strongly Correlated Electrons · Physics 2016-08-03 Kiel T. Williams , Lucas K. Wagner

Quantum computing offers a promising platform to address the computational challenges inherent in quantum chemistry, and particularly in valence bond (VB) methods, which are chemically appealing but suffer from high computational cost due…

Precise calculations of core properties in heavy-atom systems which are described by the operators heavily concentrated in atomic cores, like to hyperfine structure and P,T-parity nonconservation effects, usually require accounting for…

Atomic Physics · Physics 2015-06-26 A. V. Titov , N. S. Mosyagin , A. N. Petrov , T. A. Isaev

We present a novel route to constructing cost-efficient semi-empirical approximations for the non-additive kinetic energy in subsystem density functional theory. The developed methodology is based on the use of Slater determinants composed…

Chemical Physics · Physics 2025-01-13 Larissa Sophie Eitelhuber , Denis G. Artiukhin

We introduce a new method for computing spectra of molecules for which a spin-spin term in the Hamiltonian has an important effect. In previous calculations, matrix elements of the spin-spin term and of the potential were obtained by…

Chemical Physics · Physics 2019-05-23 Xiao-Gang Wang , Tucker Carrington

Quantum chemical calculations have attracted much attention as a practical application of quantum computing. Quantum computers can prepare superpositions of electronic states with various numbers of electrons on qubits. This special feature…

Chemical Physics · Physics 2024-03-29 Soichi Shirai , Takahiro Horiba , Hirotoshi Hirai

We propose a new variational method for describing nuclear matter from nucleon-nucleon interaction. We use the unitary correlation operator method (UCOM) for central correlation to treat the short-range repulsion and further include the…

The Hartree-Fock approximation for bosons employs variational wave functions that are a combination of permanents. These are bosonic counterpart of the fermionic Slater determinants, but with the significant distinction that the…

Quantum Gases · Physics 2025-03-03 B. R. Que , J. M. Zhang , H. F. Song , Y. Liu

The mass-correction functions in the second-order non-adiabatic Hamiltonian are computed for the $^4$He$^+_2$ molecular ion using the variational method, floating explicitly correlated Gaussian functions, and a general…

Chemical Physics · Physics 2018-12-05 Edit Mátyus