Calculating optical absorption spectra for large systems using linear-scaling density functional theory
نویسندگان
چکیده
A new method for calculating optical absorption spectra within linear-scaling density functional theory (LSDFT) is presented, incorporating a scheme for optimizing a set of localized orbitals to accurately represent unoccupied Kohn-Sham states. Three different schemes are compared and the most promising of these, based on the use of a projection operator, has been implemented in a fully functional LS-DFT code. The method has been applied to the calculation of optical absorption spectra for the metal-free phthalocyanine molecule and the conjugated polymer poly(para-phenylene). Excellent agreement with results from a traditional DFT code is obtained.
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