Lorenz, Marco and Usvyat, Denis and Schütz, Martin (2011) Local ab initio methods for calculating optical band gaps in periodic systems. I. Periodic density fitted local configuration interaction singles method for polymers. The Journal of Chemical Physics 134 (9), 094101.
|PDF - Published Version|
Other URL: http://dx.doi.org/doi/10.1063/1.3554209
We present a density fitted local configuration interaction singles (CIS) method for calculating optical band gaps in 1D-periodic systems. The method is based on the Davidson diagonalization procedure, carried out in the reciprocal space. The one-electron part of the matrix–vector products is also evaluated in the reciprocal space, where the diagonality of the Fock matrix can be exploited. The contraction of the CIS vectors with the two electron integrals is performed in the direct space in the basis of localized occupied (Wannier) and virtual (projected atomic) orbitals. The direct space approach allows to utilize the sparsity of the integrals due to the local representation and locality of the exciton. The density fitting approximation employed for the two electron integrals reduces the nominal scaling with unit cell size to O(N4). Test calculations on a series of prototypical systems demonstrate that the method in its present stage can be used to calculate the excitonic band gaps of polymers with up to a few dozens of atoms in the cell. The computational cost depends on the locality of the exciton, but even relatively delocalized excitons occurring in the polybiphenyl in the parallel orientation, can be routinely treated with this method.
|Institutions:||Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie > Research Group Theoretical Chemistry > Prof. Dr. Martin Schütz|
|Keywords:||ab initio calculations; energy gap; excitons; HF calculations; optical constants; orbital calculations; periodic structures; polymers; tight-binding calculations;|
|Subjects:||500 Science > 530 Physics|
500 Science > 540 Chemistry & allied sciences
|Refereed:||Yes, this version has been refereed|
|Created at the University of Regensburg:||Yes|
|Deposited On:||07 Sep 2011 08:25|
|Last Modified:||07 Sep 2011 08:25|