SPARC: Simulation Package for Ab-initio Real-space Calculations

Xu, Qimen; Sharma, Abhiraj; Comer, Benjamin M.; Huang, Hua; Chow, Edmond; Medford, Andrew J.; Pask, John E.; Suryanarayana, Phanish

doi:10.48550/arxiv.2005.10431

Cited by 7 publications

(12 citation statements)

References 76 publications

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“…It is however desirable for the chosen approach to efficiently simulate bending deformations commensurate with those found in experiments [15][16][17][18]. Given the large system sizes encountered, for extended structures in particular, ab initio simulation of bending deformations is particularly challenging, even with state-of-the-art DFT codes [27][28][29]. This is because DFT calculations are highly expensive, scaling cubically with system size and possessing a large prefactor, particularly when systematically improvable discretizations are used.…”

mentioning

confidence: 99%

Transversal flexoelectric coefficient for nanostructures at finite deformations from first principles

Codony

Arias

Suryanarayana

2021

Phys. Rev. Materials

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We present a novel formulation for calculating the transversal flexoelectric coefficient of nanostructures at finite deformations from first principles. Specifically, we introduce the concept of radial polarization to make the coefficient a well-defined quantity for uniform bending deformations. We use the framework to calculate the flexoelectric coefficient for group IV atomic monolayers using density functional theory. We find that graphene's coefficient is significantly larger than previously reported, with a charge transfer mechanism that differs from other members of its group.

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confidence: 99%

Transversal flexoelectric coefficient for nanostructures at finite deformations from first principles

Codony

Arias

Suryanarayana

2021

Phys. Rev. Materials

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“…We utilize the Cyclix-DFT code 44 -adaptation of the state-of-the-art real-space DFT code SPARC [57][58][59] to cylindrical and helical coordinate systems, with the ability to exploit cyclic and helical symmetry in one-dimensional nanostructures 44,60,61 -to calculate the torsional moduli of the aforementioned TMD nanotubes in the low twist limit. Specifically, we consider three-atom unit cell/fundamental domains that has one metal atom and two chalcogen atoms, as illustrated in Fig.…”

Section: Systems and Methodsmentioning

confidence: 99%

“…1. Indeed, such calculations are impractical without the symmetry adaption, e.g., a (57,57) MoS 2 nanotube (diameter ∼ 10 nm) with an external twist of 2 × 10 -4 rad/Bohr has 234, 783 atoms in the simulation domain when employing periodic boundary conditions, well beyond the reach of even state-of-the-art DFT codes on large-scale parallel machines 57,62,63 . It is worth noting that the Cyclix-DFT code has already been successfully employed for the study of physical applications 44,[64][65][66] , which provides evidence of its accuracy.…”

Section: Systems and Methodsmentioning

confidence: 99%

Torsional moduli of transition metal dichalcogenide nanotubes from first principles

Bhardwaj,

Sharma,

Suryanarayana

2021

Preprint

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We calculate the torsional moduli of single-walled transition metal dichalcogenide (TMD) nanotubes using ab initio density functional theory (DFT). Specifically, considering forty-five select TMD nanotubes, we perform symmetry-adapted DFT calculations to calculate the torsional moduli for the armchair and zigzag variants of these materials in the low-twist regime and at practically relevant diameters. We find that the torsional moduli follow the trend: MS 2 > MSe 2 > MTe 2 . In addition, the moduli display a power law dependence on diameter, with the scaling generally close to cubic, as predicted by the isotropic elastic continuum model. In particular, the shear moduli so computed are in good agreement with those predicted by the isotropic relation in terms of the Young's modulus and Poisson's ratio, both of which are also calculated using symmetry-adapted DFT. Finally, we develop a linear regression model for the torsional moduli of TMD nanotubes based on the nature/characteristics of the metal-chalcogen bond, and show that it is capable of making reasonably accurate predictions.

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“…To facilitate rapid implementation and testing, we formulate and implement the self-interaction correction in real space in the M-SPARC prototype code, 81 a serial implementation of the massively parallel SPARC real-space electronic structure code, [82][83][84] sharing the same structure, algorithms, input, and output.…”

Section: Real-space Formulation and Implementation A M-sparc Code Basementioning

confidence: 99%

Implementation of Perdew–Zunger self-interaction correction in real space using Fermi–Löwdin orbitals

Diaz

Suryanarayana

et al. 2021

The Journal of Chemical Physics

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Most widely used density functional approximations suffer from self-interaction (SI) error, which can be corrected using the Perdew-Zunger (PZ) self-interaction correction (SIC). We implement the recently proposed size-extensive formulation of PZ-SIC using Fermi-Löwdin Orbitals (FLOs) in real space, which is amenable to systematic convergence and large-scale parallelization. We verify the new formulation within the generalized Slater scheme by computing atomization energies and ionization potentials of selected molecules and comparing to those obtained by existing FLOSIC implementations in Gaussian based codes. The results show good agreement between the two formulations, with new real-space results somewhat closer to experiment on average for the systems considered. We also obtain the ionization potentials and atomization energies by scaling down the Slater statistical average of SIC potentials. The results show that scaling down the average SIC potential improves both atomization energies and ionization potentials, bringing them closer to experiment. Finally, we verify the present formulation by calculating the barrier heights of chemical reactions in the BH6 dataset, where significant improvements are obtained relative to Gaussian based FLOSIC results.

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SPARC: Simulation Package for Ab-initio Real-space Calculations

Cited by 7 publications

References 76 publications

Transversal flexoelectric coefficient for nanostructures at finite deformations from first principles

Transversal flexoelectric coefficient for nanostructures at finite deformations from first principles

Torsional moduli of transition metal dichalcogenide nanotubes from first principles

Implementation of Perdew–Zunger self-interaction correction in real space using Fermi–Löwdin orbitals

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