Natural Orbitals for Wave Function Based Correlated Calculations Using a Plane Wave Basis Set

• DOI: 10.1021/ct200263g
• Publication Date: 2011-07-05T20:55:08Z
• Authors: Andreas Grüneis; George H. Booth; Martijn Marsman; James Spencer; Ali Alavi; Georg Kresse
• Keywords: 103009 Festkörperphysik; 103025 Quantenmechanik; 104022 Theoretical chemistry; 104022 Theoretische Chemie; 103018 Materialphysik; 103025 Quantum mechanics; 02 engineering and technology; 0210 nano-technology; 103018 Materials physics; 7. Clean energy; 103009 Solid state physics

We demonstrate that natural orbitals allow for reducing the computational cost of wave function based correlated calculations, especially for atoms and molecules in a large box, when a plane wave basis set under periodic boundary conditions is used. The employed natural orbitals are evaluated on the level of second-order Møller-Plesset perturbation theory (MP2), which requires a computational effort that scales as [Formula: see text](N(5)), where N is a measure of the system size. Moreover, we find that a simple approximation reducing the scaling to [Formula: see text](N(4)) yields orbitals that allow for a similar reduction of the number of virtual orbitals. The MP2 natural orbitals are applied to coupled-cluster singles and doubles (CCSD) as well as full configuration interaction Quantum Monte Carlo calculations of the H2 molecule to test our implementation. Finally, the atomization energies of the LiH molecule and solid are calculated on the level of MP2 and CCSD.