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Quantum mechanical calculations for material modelling using Kohn-Sham density functional theory (DFT) involve the solution of a nonlinear eigenvalue problem for $N$ smallest eigenvector-eigenvalue pairs with $N$ proportional to the number…

Computational Physics · Physics 2023-09-26 Sameer Khadatkar , Phani Motamarri

We propose a multipole representation of the Fermi-Dirac function and the Fermi operator, and use this representation to develop algorithms for electronic structure analysis of metallic systems. The new algorithm is quite simple and…

Materials Science · Physics 2010-10-26 Lin Lin , Jianfeng Lu , Roberto Car , Weinan E

We showcase the advantages of orbital-free density-potential functional theory (DPFT), a more flexible variant of Hohenberg-Kohn density functional theory. DPFT resolves the usual trouble with the gradient-expanded kinetic energy functional…

Quantum Gases · Physics 2021-06-16 Martin-Isbjörn Trappe , Jun Hao Hue , Berthold-Georg Englert

Charret et. al. applied the properties of the Grassmann generators to develop a new method to calculate the coefficients of the high temperature expansion of the grand canonical partition function of self-interacting fermionic models in any…

High Energy Physics - Theory · Physics 2016-09-06 S. M. de Souza , O. Rojas Santos , M. T. Thomaz

In this work we present a novel quantum Monte-Carlo method for fermions, based on an exact decomposition of the Boltzmann operator $exp(-\beta H)$. It can be seen as a synthesis of several related methods. It has the advantage that it is…

Strongly Correlated Electrons · Physics 2009-10-31 S. Rombouts , K. Heyde , N. Jachowicz

The nuclear energy density functional method at finite temperature is a useful tool for studies of nuclear structure at high excitation, and also for researches of nuclear matter involved in explosive stellar phenomena and neutron stars.…

Nuclear Theory · Physics 2023-03-02 Takashi Nakatsukasa

We present a spectrum-splitting approach to conduct all-electron Kohn-Sham density functional theory (DFT) calculations by employing Fermi-operator expansion of the Kohn-Sham Hamiltonian. The proposed approach splits the subspace containing…

Computational Physics · Physics 2017-02-01 Phani Motamarri , Vikram Gavini , Kaushik Bhattacharya , Michael Ortiz

We present a numerical method for grand canonical density functional theory (DFT) tailored to solid-state systems, employing Gaussian-type orbitals as the primary basis. Our approach directly minimizes the grand canonical free energy using…

Chemical Physics · Physics 2025-10-09 Anton Z. Ni , Adam Rettig , Joonho Lee

Achieving an accurate description of fermionic systems typically requires considerably many more orbitals than fermions. Previous resource analyses of quantum chemistry simulation often failed to exploit this low fermionic number…

Quantum Physics · Physics 2022-05-24 Sam McArdle , Earl Campbell , Yuan Su

For any d-dimensional self-interacting fermionic model, all coefficients in the high-temperature expansion of its grand canonical partition function can be put in terms of multivariable Grassmann integrals. A new approach to calculate such…

Statistical Mechanics · Physics 2015-06-25 I. C. Charret , E. V. Corrêa Silva , S. M. de Souza , O. Rojas Santos , M. T. Thomaz

In a recent paper we have suggested that the finite temperature density matrix can be computed efficiently by a combination of polynomial expansion and iterative inversion techniques. We present here significant improvements over this…

Materials Science · Physics 2010-10-19 Michele Ceriotti , Thomas D. Kühne , Michele Parrinello

We derive a rigorous, quantum mechanical map of fermionic creation and annihilation operators to continuous Cartesian variables that exactly reproduces the matrix structure of the many-fermion problem. We show how our scheme can be used to…

Chemical Physics · Physics 2018-03-20 Andrés Montoya-Castillo , Thomas E. Markland

I solve a quantum chain whose Hamiltonian is comprised solely of local four-fermi operators by constructing free-fermion raising and lowering operators. The free-fermion operators are both non-local and highly non-linear in the local…

Statistical Mechanics · Physics 2019-11-06 Paul Fendley

Large scale Density Functional Theory (DFT) based electronic structure calculations are highly time consuming and scale poorly with system size. While semi-empirical approximations to DFT result in a reduction in computational time versus…

Materials Science · Physics 2016-12-21 Ganesh Hegde , R. Chris Bowen

We exploit the grassmannian nature of the variables involved in the path integral expression of the grand canonical partition function for self--interacting fermionic models to show, in one-space dimension, a general relation among the…

Condensed Matter · Physics 2016-08-31 I. C. Charret , S. M. de Souza , M. T. Thomaz , E. V. Correa Silva

We propose an efficient quantum algorithm for simulating the dynamics of general Hamiltonian systems. Our technique is based on a power series expansion of the time-evolution operator in its off-diagonal terms. The expansion decouples the…

Quantum Physics · Physics 2021-06-22 Amir Kalev , Itay Hen

A purification algorithm for expanding the single-particle density matrix in terms of the Hamiltonian operator is proposed. The scheme works with a predefined occupation and requires less than half the number of matrix-matrix…

Materials Science · Physics 2009-11-07 Anders M. N. Niklasson

We present a quantum algorithm for the dynamical simulation of time-dependent Hamiltonians. Our method involves expanding the interaction-picture Hamiltonian as a sum of generalized permutations, which leads to an integral-free Dyson series…

Quantum Physics · Physics 2021-09-15 Yi-Hsiang Chen , Amir Kalev , Itay Hen

The development of machine learning sheds new light on the problem of statistical thermodynamics in multicomponent alloys. However, a data-driven approach to construct the effective Hamiltonian requires sufficiently large data sets, which…

Materials Science · Physics 2020-01-01 Xianglin Liu , Jiaxin Zhang , Markus Eisenbach , Yang Wang

Time-dependent orbital-free DFT is an efficient method for calculating the dynamic properties of large scale quantum systems due to the low computational cost compared to standard time-dependent DFT. We formalize this method by mapping the…

Chemical Physics · Physics 2021-06-09 Kaili Jiang , Michele Pavanello
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