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Quasiparticle Spectra from a Nonempirical Optimally Tuned Range-Separated Hybrid Density Functional


  Sivan Refaely-Abramson [1]  ,  Sahar Sharifzadeh [2]  ,  Niranjan Govind [3]  ,  Jochen Autschbach [4]  ,  Jeffrey B. Neaton [2]  ,  Roi Baer [5]  ,  Leeor Kronik [1]  
 [1] Department of Materials and Interfaces, Weizmann Institute of Science, Rehovoth 76100, Israel
[2] Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
[3] William R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
[4] Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260-3000, USA
[5] Fritz Haber Center for Molecular Dynamics, Institute of Chemistry, Hebrew University, Jerusalem 91904, Israel

We present a method for obtaining outer-valence quasiparticle excitation energies from a density-functional-theory-based calculation, with an accuracy that is comparable to that of many-body perturbation theory within the GW approximation. The approach uses a range-separated hybrid density functional, with an asymptotically exact and short-range fractional Fock exchange. The functional contains two parameters, the range separation and the short-range Fock fraction. Both are determined nonempirically, per system, on the basis of the satisfaction of exact physical constraints for the ionization potential and many-electron self-interaction, respectively. The accuracy of the method is demonstrated on four important benchmark organic molecules: perylene, pentacene, 3,4,9,10-perylene-tetracarboxylic dianhydride (PTCDA), and 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTCDA). We envision that for finite systems the approach could provide an inexpensive alternative to GW, opening the door to the study of presently out of reach large-scale systems.