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We present an efficient preconditioning technique for accelerating the fixed point iteration in real-space Kohn-Sham density functional theory (DFT) calculations. The preconditioner uses a low rank approximation of the dielectric matrix…

Materials Science · Physics 2023-03-29 Sambit Das , Vikram Gavini

We present an accurate, efficient and massively parallel finite-element code, DFT-FE, for large-scale ab-initio calculations (reaching $\sim 100,000$ electrons) using Kohn-Sham density functional theory (DFT). DFT-FE is based on a local…

Computational Physics · Physics 2020-01-08 Phani Motamarri , Sambit Das , Shiva Rudraraju , Krishnendu Ghosh , Denis Davydov , Vikram Gavini

Nonequispaced discrete Fourier transformation (NDFT) is widely applied in all aspects of computational science and engineering. The computational efficiency and accuracy of NDFT has always been a critical issue in hindering its…

Mathematical Software · Computer Science 2020-08-06 Sheng-Chun Yang , Yong-Lei Wang

Linear-scaling implementations of density functional theory (DFT) reach their intended efficiency regime only when applied to systems having a physical size larger than the range of their Kohn-Sham density matrix (DM). This causes a problem…

Chemical Physics · Physics 2022-03-25 Marcel David Fabian , Ben Shpiro , Eran Rabani , Daniel Neuhauser , Roi Baer

Recommendation systems, social network analysis, medical imaging, and data mining often involve processing sparse high-dimensional data. Such high-dimensional data are naturally represented as tensors, and they cannot be efficiently…

Distributed, Parallel, and Cluster Computing · Computer Science 2020-10-22 Weiyun Jiang , Kaiqi Zhang , Colin Yu Lin , Feng Xing , Zheng Zhang

With the growing reliance of modern supercomputers on accelerator-based architectures such a GPUs, the development and optimization of electronic structure methods to exploit these massively parallel resources has become a recent priority.…

Density Functional Theory (DFT) has become the quasi-standard for ab-initio simulations for a wide range of applications. While the intrinsic cubic scaling of DFT was for a long time limiting the accessible system size to some hundred…

Materials Science · Physics 2018-02-23 Stephan Mohr , Marc Eixarch , Maximilian Amsler , Mervi J. Mantsinen , Luigi Genovese

We present an efficient post-processing method for calculating the electronic structure of nanosystems based on the divide-and-conquer approach to density functional theory (DC-DFT), in which a system is divided into subsystems whose…

Materials Science · Physics 2017-01-06 Shunsuke Yamada , Fuyuki Shimojo , Ryosuke Akashi , Shinji Tsuneyuki

Ultrafast electronic dynamics in solids lies at the core of modern condensed matter and materials physics. To build up a practical ab initio method for studying solids under photoexcitation, we develop a momentum-resolved real-time time…

Materials Science · Physics 2018-10-17 Chao Lian , Shi-Qi Hu , Meng-Xue Guan , Sheng Meng

The predominance of Kohn-Sham density functional theory (KS-DFT) for the theoretical treatment of large experimentally relevant systems in molecular chemistry and materials science relies primarily on the existence of efficient software…

Computational Physics · Physics 2020-07-08 David B. Williams-Young , Wibe A. de Jong , Hubertus J. J. van Dam , Chao Yang

Real time, density matrix based, time dependent density functional theory proceeds through the propagation of the density matrix, as opposed to the Kohn-Sham orbitals. It is possible to reduce the computational workload by imposing spatial…

Computational Physics · Physics 2015-05-20 Conn O'Rourke , David R. Bowler

Over many years, computational simulations based on Density Functional Theory (DFT) have been used extensively to study many different materials at the atomic scale. However, its application is restricted by system size, leaving a number of…

Mesoscale and Nanoscale Physics · Physics 2018-12-05 Carlos Romero-Muñiz , Ayako Nakata , Pablo Pou , David R. Bowler , Tsuyoshi Miyazaki , Rubén Pérez

We revisit Kohn-Sham time-dependent density-functional theory (TDDFT) equations and show that they derive from a canonical Hamiltonian formalism. We use this geometric description of the TDDFT dynamics to define families of symplectic…

Computational Physics · Physics 2023-11-20 Francois Mauger , Cristel Chandre , Mette B. Gaarde , Kenneth Lopata , Kenneth J. Schafer

We develop a method in which the electronic densities of small fragments determined by Kohn-Sham density functional theory (DFT) are embedded using stochastic DFT to form the exact density of the full system. The new method preserves the…

Chemical Physics · Physics 2015-06-19 Daniel Neuhauser , Roi Baer , Eran Rabani

One route to numerically propagating quantum systems is time-dependent density functional theory (TDDFT). The application of TDDFT to a particular system's time evolution is predicated on $V$-representability which we have analyzed in a…

Quantum Physics · Physics 2020-10-27 James Brown , Jun Yang , James D Whitfield

Imaginary-time time-dependent Density functional theory (it-TDDFT) has been proposed as an alternative method for obtaining the ground state within density functional theory (DFT) which avoids some of the difficulties with convergence…

Computational Physics · Physics 2021-11-09 John McFarland , Efstratios Manousakis

Noncollinear (NC) magnetism and spin-orbit coupling (SOC) are indispensable for predictive ab initio materials simulations with pronounced relativistic effects and magnetic frustration, yet they significantly increase the cost of…

This chapter provides a basic introduction to excited-state extensions of density functional theory (DFT), including time-dependent (TD-)DFT in both its linear-response and its explicitly time-dependent formulations. As applied to the…

Chemical Physics · Physics 2023-05-02 John M. Herbert

Tucker decomposition is one of the most popular models for analyzing and compressing large-scale tensorial data. Existing Tucker decomposition algorithms usually rely on a single solver to compute the factor matrices and core tensor, and…

Distributed, Parallel, and Cluster Computing · Computer Science 2020-10-21 Min Li , Chuanfu Xiao , Chao Yang

We present a new method to accelerate real time-time dependent density functional theory (rt-TDDFT) calculations with hybrid exchange-correlation functionals. For large basis set, the computational bottleneck for large scale calculations is…

Computational Physics · Physics 2019-07-24 Weile Jia , Lin Lin