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1.
A new algorithm for density-functional-theory-based ab initio molecular dynamics simulations is presented. The Kohn–Sham
orbitals are expanded in Gaussian-type functions and an augmented-plane-wave-type approach is used to represent the electronic
density. This extends previous work of ours where the density was expanded only in plane waves. We describe the total density
in a smooth extended part which we represent in plane waves as in our previous work and parts localised close to the nuclei
which are expanded in Gaussians. Using this representation of the charge we show how the localised and extended part can be
treated separately, achieving a computational cost for the calculation of the Kohn–Sham matrix that scales with the system
size N as O(NlogN). Furthermore, we are able to reduce drastically the size of the plane-wave basis. In addition, we introduce a multiple-cutoff
method that improves considerably the performance of this approach. Finally, we demonstrate with a series of numerical examples
the accuracy and efficiency of the new algorithm, both for electronic structure calculations and for ab initio molecular dynamics
simulations.
Received: 15 December 1998 /Accepted: 18 February 1999 /Published online: 14 July 1999 相似文献
2.
Toward assessment of density functionals for vibronic coupling in two‐photon absorption: A case study of 4‐nitroaniline 下载免费PDF全文
Robert Zaleśny Guangjun Tian Christof Hättig Wojciech Bartkowiak Hans Ågren 《Journal of computational chemistry》2015,36(15):1124-1131
In this study, we predict vibronic two‐photon absorption (TPA) spectra for 4‐nitroaniline in vacuo. The simulations are performed using density functional theory and the approximate second‐order coupled‐cluster singles and doubles model CC2. Thereby we also demonstrate the possibility of simulations of vibronic TPA spectra with ab initio wavefunction methods that include electron correlation for medium‐sized systems. A special focus is put on the geometric derivatives of the second‐order transition moment and the dipole moment difference between the charge‐transfer excited state and the ground state. The results of CC2 calculations bring new insight into the vibronic coupling mechanism in TPA spectra of 4‐nitroniline and demonstrate that the mixed term is quite large and that it also exhibits a negative interference with the Franck‐Condon contribution. © 2015 Wiley Periodicals, Inc. 相似文献
3.
G.G. Camiletti A. Canal Neto F.E. Jorge S.F. Machado 《Journal of Molecular Structure》2009,910(1-3):122-125
Augmented Gaussian basis sets of double and triple zeta valence qualities plus polarization functions for the atoms K and from Sc to Kr are presented. They were generated from the all-electron unaugmented sets by addition of diffuse functions (s, p, d, f, and g symmetries) that were optimized for the anion ground states. From these sets, Hartree–Fock, second-order Møller–Plesset perturbation theory, and density functional theory electric dipole moment and dipole polarizability calculations for a sample of molecules were carried out. Comparison with theoretical and experimental values available in the literature was done. 相似文献