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Manual Pseudopotentials and orbitals Examples



Chapter 1 Introduction


ABACUS (Atomic-orbtial Based Ab-initio Computation at UStc) is an open-source computer code package aiming at large-scale electronic-structure simulations from first principles, developed at the Key Laboratory of Quantum Information, Unviersity of Science and Technology of China (USTC). ABACUS uses norm-conserving pseudopotentials to describe the interactions between nuclear ions and valence electrons. As its name indicates, ABACUS primarily employs numerically tabulated atom-centered orbitals as its basis functions to expand electronic wave functions. These basis functions are generated using an optimization scheme developed by Chen, Guo, and He (CGH) [1] early on, and form a series of hierarchical basis sets, through
which the computational accuracy can be systematically improved by increasing the basis set size. Besides atomic basis sets, ABACUS also allows to use plane-wave basis set as an alternative option. This dual basis-set feature allows for a convenient consistency and accuracy check within ABACUS.


Currently ABACUS provides the following features and functionalities.


• Ground-state total energy calculations using Kohn-Sham (KS) density functional theory

(DFT) [2, 3] with local-density or generalized gradient approximations (LDA/GGAs).
Brillouin zone sampling using the Monkhorst-Pack special k-points [4].
Geometry relaxation with both Conjugated Gradient (CG) and BroydenFletcherGoldfarb- Shanno (BFGS) [5] methods.
Semi-emperical van der Waals energy correction using the Grimme DFT-D2 [6] scheme.
NVT molecular dynamics simulation using the Nos´e-Hoover thermostat [7].

Other functionalities including hybrid density functionals and time-dependent DFT are under active development, and will be available for the next release.

ABACUS can run both on desktop computers and high performance supercomputers, for the moment under the unit/linux-based environment. It scales up to O(10^3) CPU cores.

For any use of ABACUS, please cite the following paper,

[1] M. Chen, G-C Guo, and L. He, Systematically improvable optimized atomic sets for ab initio calculations, J. Phys.: Condens. Matter 22, 445501(2010).
[2] P. F. Li, X. H. Liu, M. H. Chen, P. Z. Lin, X. G. Ren, L. Lin, and L. He, Large-scale ab initio simulations based on systematically improvable atomic

basis, Comput.Mater. Sci., in print; DOI:10.1016/j.commatsci.2015.07.004


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