Berlin 2012 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 20: Theoretical methods I

O 20.3: Vortrag

Montag, 26. März 2012, 18:15–18:30, A 060

Implementation of screened hybrid density functionals for periodic systems with numerical atomic orbitals:Basis function fitting and integral screening — •Honghui Shang and Jinlong Yang — University of Science and Technology of China, Hefei, China

In hybrid functional calculations of the electronic structure, evaluation of the Hartree-Fock exchange (HFX) is currently the computational bottleneck. Although the scaling with system size can be linear when numerical atomic orbitals (NAOs) are used, the computation of HFX carries a large prefactor. The development of efficient algorithms that reduce the prefactor therefore becomes crucial. In this work, an efficient O(N) implementation of screened hybrid density functionals is presented for periodic systems. NAOs of valence electrons are fitted with gaussian type orbitals (GTOs), which can be used for an analytical evaluation of the electron repulsion integrals (ERIs) that are the building blocks of HFX. The strict locality of the NAOs is employed for an efficient two-electron integral screening technique. In this way, the prefactor of HFX is significantly reduced while retaining the O(N) scaling. This hybrid scheme, denoted as NAO2GTO, is implemented in the SIESTA package. We have tested our method for a variety of systems ranging from molecules to solids. When the DZP basis set is used, good agreement with results obtained from plane wave packages is reached. Our implementation, for the first time, enables screened hybrid functional calculations using NAOs for non-trivial periodic systems.
*present addess: Fritz-Haber-Institut der MPG, Berlin