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We show that a rectangular collocation method, equivalent to evaluating all matrix elements with a quadrature-like scheme and using more points than basis functions, is an effective approach for solving the electronic Schr\"odinger equation…

Computational Physics · Physics 2021-12-08 Sergei Manzhos , Tucker Carrington

The q-Gaussian distribution results from maximizing certain generalizations of Shannon entropy under some constraints. The importance of q-Gaussian distributions stems from the fact that they exhibit power-law behavior, and also generalize…

Systems and Control · Computer Science 2013-11-12 Debarghya Ghoshdastidar , Ambedkar Dukkipati , Shalabh Bhatnagar

The generalized eigenvalue (GE) problems are of particular importance in various areas of science engineering and machine learning. We present a variational quantum algorithm for finding the desired generalized eigenvalue of the GE problem,…

Quantum Physics · Physics 2022-03-08 Jin-Min Liang , Shu-Qian Shen , Ming Li , Shao-Ming Fei

Using quasiparticle self-consistent $GW$ calculations, we re-examined the electronic structure of Sr$_2$RuO$_4$ and SrRuO$_3$. Our calculations show that the correlation effects beyond the conventional LDA (local density approximation) and…

Strongly Correlated Electrons · Physics 2016-02-16 Hyeonsang Ryee , Seung Woo Jang , Hiori Kino , Takao Kotani , Myung Joon Han

Often the easiest way to discretize an ordinary or partial differential equation is by a rectangular numerical method, in which n basis functions are sampled at m>>n collocation points. We show how eigenvalue problems can be solved in this…

Numerical Analysis · Mathematics 2021-12-28 Behnam Hashemi , Yuji Nakatsukasa , Lloyd N. Trefethen

The quasiparticle self-consistent QS$GW$ approach incorporates the corrections of the quasiparticle energies from their Kohn-Sham density functional theory (DFT) eigenvalues by means of an energy independent and Hermitian self-energy matrix…

Materials Science · Physics 2022-06-08 Ozan Dernek , Dmitry Skachkov , Walter R. L. Lambrecht , Mark van Schilfgaarde

Solving the generalized eigenvalue problem is a useful method for finding energy eigenstates of large quantum systems. It uses projection onto a set of basis states which are typically not orthogonal. One needs to invert a matrix whose…

Nuclear Theory · Physics 2023-04-05 Caleb Hicks , Dean Lee

We have developed a new type of self-consistent scheme within the $GW$ approximation, which we call quasiparticle self-consistent $GW$ (QS$GW$). We have shown that QS$GW$ rather well describes energy bands for a wide-range of materials,…

Materials Science · Physics 2007-10-05 Takao Kotani , Mark van Schilfgaarde , Sergey V. Faleev

We present a quasiparticle self-consistent $GW$ (QSGW) implementation for periodic systems based on crystalline Gaussian basis sets. Our QSGW approach is based on a full-frequency analytic continuation GW scheme with Brillouin zone sampling…

Chemical Physics · Physics 2022-12-21 Jincheng Lei , Tianyu Zhu

Extended free energy Lagrangians are proposed for first principles molecular dynamics simulations at finite electronic temperatures for plane-wave pseudopotential and local orbital density matrix based calculations. Thanks to the extended…

Chemical Physics · Physics 2011-11-02 Anders M. N. Niklasson , Peter Steneteg , Nicolas Bock

A parallel implementation of an eigensolver designed for electronic structure calculations is presented. The method is applicable to computational tasks that solve a sequence of eigenvalue problems where the solution for a particular…

Computational Physics · Physics 2015-03-02 E. L. Briggs , C. T. Kelley , J. Bernholc

We introduce an alternative route to quasiparticle self-consistent $GW$ calculations ($\mathrm{qs}GW$) on the basis of a Joint Approximate Diagonalization of the one-body $GW$ Green's functions $G(\varepsilon_n^{QP})$ taken at the input…

Materials Science · Physics 2024-12-05 Ivan Duchemin , Xavier Blase

Vibrational properties of molecular crystals are constantly used as structural fingerprints, in order to identify both the chemical nature and the structural arrangement of molecules. The simulation of these properties is typically very…

Computational Physics · Physics 2019-10-09 Nathaniel Raimbault , Andrea Grisafi , Michele Ceriotti , Mariana Rossi

Numerical simulations of waves in highly heterogeneous media have important applications, but direct computations are prohibitively expensive. In this paper, we develop a new generalized multiscale finite element method with the aim of…

Numerical Analysis · Mathematics 2015-09-09 Eric T. Chung , Wing Tat Leung

In this work, we propose a quantum unitary downfolding formalism based on the driven similarity renormalization group (QDSRG) that may be combined with quantum algorithms for both noisy and fault-tolerant hardware. The QDSRG is a classical…

Quantum Physics · Physics 2022-08-19 Renke Huang , Chenyang Li , Francesco A. Evangelista

With the aim of describing bound and continuum states for diatomic molecules, we develop and implement a spectral method that makes use of Generalized Sturmian Functions (GSF) in prolate spheroidal coordinates. In order to master all…

Atomic and Molecular Clusters · Physics 2021-06-02 D. M. Mitnik , F. A. Lopez , L. U. Ancarani

We present a methodology for computing vibrationally and time-resolved pump-probe spectra, which takes into account all vibrational degrees of freedom and is based on the combination of the thawed Gaussian approximation with on-the-fly ab…

Chemical Physics · Physics 2019-01-31 Tomislav Begušić , Julien Roulet , Jiří Vaníček

We propose a meshless conservative Galerkin method for solving Hamiltonian wave equations. We first discretize the equation in space using radial basis functions in a Galerkin-type formulation. Differ from the traditional RBF Galerkin…

Numerical Analysis · Mathematics 2022-09-20 Zhengjie Sun , Leevan Ling

We present a fully numerical framework for the optimization of molecule-specific quantum chemical basis functions within the quantics tensor train format using a finite-difference scheme. The optimization is driven by solving the…

Chemical Physics · Physics 2025-06-12 Paul Haubenwallner , Matthias Heller

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.…