Optical Absorption in Molecular Crystals from Time-Dependent Density Functional Theory
Technical Report,01 Sep 2015,31 Aug 2016
Weizmann Institue of Science Rehovot United States
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We address a major challenge for computational materials science based on density functional theory, by showing that fundamental gaps and optical spectra of molecular solids can be predicted quantitatively and non-empirically within the framework of time-dependent density functional theory TDDFT, using the recently-developed optimally-tuned screened range-separated hybrid OTSRSH approach. We provide a comprehensive benchmark for the accuracy of our approach by considering the X23 set of molecular solids and comparing results obtained from TDDFT with those obtained from many-body perturbation theory in the GW-BSE approximation. We additionally compare results obtained from dielectric screening computed within the random phase approximation to those obtained from the computationally easier many-body dispersion approach and find that this influences the fundamental gap but there is little effect on the optical spectra. We therefore believe that the method is robust and can be used for studies of molecular solids that are typically outside the reach of computationally more intensive methods.
- Physical Chemistry