On the Kohn-Sham density response in a localized basis set.
We construct the Kohn-Sham density response function chi(0) in a previously described basis of the space of orbital products. The calculational complexity of our construction is O(N(2)N(omega)) for a molecule of N atoms and in a spectroscopic window of N(omega) frequency points. As a first application, we use chi(0) to calculate the molecular spectra from the Petersilka-Gossmann-Gross equation. With chi(0) as input, we obtain the correct spectra with an extra computational effort that grows also as O(N(2)N(omega)) and, therefore, less steeply in N than the O(N(3)) complexity of solving Casida's equations. Our construction should be useful for the study of excitons in molecular physics and in related areas where chi(0) is a crucial ingredient.
Foerster
Dietrich
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CPMOH, University of Bordeaux 1, 351 Cours de la Liberation, 33405 Talence, France. d.foerster@cpmoh.u-bordeaux1.fr
Koval
Peter
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