Ionic forces and stress tensor in all-electron density functional theory calculations using an enriched finite-element basis

Rufus, Nelson D.; Gavini, Vikram

doi:10.1103/physrevb.106.085108

Cited by 3 publications

(2 citation statements)

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“…Given the importance of relativistic effects in allelectron calculations, our future work will involve an extension of the proposed EFE basis to incorporate both scalar relativistic and spin−orbit coupling effects. Further, we intend to combine the configurational forces formulation for EFE basis 112 to enable efficient all-electron TDDFT-based Ehrenfest dynamics calculations. Lastly, the EFE basis paves the way for an efficient and systematic route to study the transferability of widely used pseudopotentials for electron dynamics.…”

Section: Discussionmentioning

confidence: 99%

“…Given the various shortcomings of existing basis sets for all-electron TDDFT calculations, an efficient, systematically convergent, and highly parallelizable basis is desirable. The current work seeks to address this gap by employing an efficient mixed basis, termed enriched finite element (EFE) basis, that has recently developed in the context of DFT calculations. − The EFE basis augments the classical/standard FE (CFE) basis with a compactly supported numerical atom-centered basis, known as enrichment functions. In effect, the EFE basis combines the efficiency of the atomic orbitals to capture the essential features of the electronic fields near the nuclei with the completeness of the FE basis.…”

Section: Introductionmentioning

confidence: 99%

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Efficient All-Electron Time-Dependent Density Functional Theory Calculations Using an Enriched Finite Element Basis

Kanungo

Rufus

Gavini

2023

J. Chem. Theory Comput.

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We present an efficient and systematically convergent approach to all-electron real-time time-dependent density functional theory (TDDFT) calculations using a mixed basis, termed as enriched finite element (EFE) basis. The EFE basis augments the classical finite element basis (CFE) with a compactly supported numerical atom-centered basis, obtained from atomic ground-state DFT calculations. Particularly, we orthogonalize the enrichment functions with respect to the classical finite element basis to ensure good conditioning of the resultant basis. We employ the second-order Magnus propagator in conjunction with an adaptive Krylov subspace method for efficient time evolution of the Kohn–Sham orbitals. We rely on a priori error estimates to guide our choice of an adaptive finite element mesh as well as the time step to be used in the TDDFT calculations. We observe close to optimal rates of convergence of the dipole moment with respect to spatial and temporal discretizations. Notably, we attain a 50–100 times speedup for the EFE basis over the CFE basis. We also demonstrate the efficacy of the EFE basis for both linear and nonlinear responses by studying the absorption spectra in sodium clusters, the linear to nonlinear response transition in the green fluorescence protein chromophore, and the higher harmonic generation in the magnesium dimer. Lastly, we attain good parallel scalability of our numerical implementation of the EFE basis for up to ∼1000 processors, using a benchmark system of a 50-atom sodium nanocluster.

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Section: Discussionmentioning

confidence: 99%