Droghetti, A*; Rungger, I; Das Pemmaraju, C*; Sanvito, S* (2016) Fundamental gap of molecular crystals via constrained density functional theory. Phys. Rev. B, 93 (19). 195208

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Abstract

The energy gap of a molecular crystal is one of the most important properties since it determines the crystal charge transport when the material is utilized in electronic devices. This is, however, a quantity difficult to calculate and standard theoretical approaches based on density functional theory (DFT) have proven unable to provide accurate estimates. In fact, besides the well-known band gap problem, DFT completely fails in capturing the fundamental gap renormalization occurring when molecules are packed in a crystal structures. The failure has to be associated to the inability of describing the electronic polarization and the real space localization of the charged states. Here we describe a scheme based on constrained DFT, which can improve upon the shortcomings of standard DFT. The method is applied to the benzene crystal, where we show that accurate results can be achieved for both the band gap and also the energy level alignment.

Item Type:	Article
Keywords:	Organic electronics, density functional theory, electron injection barriers
Subjects:	Advanced Materials Advanced Materials > Materials Modelling
Identification number/DOI:	10.1103/PhysRevB.93.195208
Last Modified:	02 Feb 2018 13:13
URI:	http://eprintspublications.npl.co.uk/id/eprint/7096

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