Screened optimally tuned range separated hybrid functional for solvated low bandgap molecular systems

Author(s)

Dantas Filho, Reinaldo V. ; de Queiroz, Thiago B.

• Document type: Journal article
• Source: Journal of Chemical Physics; v. 161, n. 3, p. 10-pg., 2024-07-21.

Abstract

The description of electronic properties of low bandgap molecular system is often performed by using density functional theory (DFT) and time dependent (TD) DFT calculations with the optimally tuned range-separated hybrid (OT-RSH) functional, as it contains the necessary ingredients to reliably predict charge transfer excitations. However, the range separating parameter (omega) is system-dependent and its optimization, including the chemical environment, is intricate. Refaely-Abramson et al. demonstrated that the gap renormalization in molecular crystals, a ground state property, can be represented by an OT-RSH functional screened by epsilon(static) [Phys. Rev. B 88, 081204(R) (2013)], the zero frequency scalar dielectric constant. In this study, we propose the use of an OT-RSH functional screened by the scalar dielectric constant in the high frequency limit (OT-sRSH), epsilon(infinity), an appropriate constraint for vertical ionization energies or excitations in a dielectric environment. We have performed calculations for S,N-heteroacene derivatives in tetrahydrofuran and dichloromethane. The "unscreened" OT-RSH functional tends to underestimate experimental ionization potentials (IPs) and optical gaps (E(g)s) by up to 1.5 and 0.5 eV, respectively. In contrast, OT-sRSH functional calculations underestimate IPs and E(g)s by only 0.4 and 0.2 eV. We also compared the OT-sRSH results to explicitly solvated OT-RSH functional calculations for oligothiophenes in dioxane, benzene in ammonia, and methylene blue in water. We observe that both the approaches perform similarly for weakly interacting intermolecular systems and deviate for solvent-solute interacting systems, as expected. In conclusion, the OT-sRSH functional can describe molecular systems with environmental polarization effects accurately, a step toward describing realistic molecular systems. (AU)

• FAPESP's process: 22/03461-8 - Time-dependent density functional theory approximations for charge separation processes
• Grantee: Reinaldo Vieira Dantas Filho
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• FAPESP's process: 20/13466-1 - Design, synthesis and characterization of molecular systems for light harvesting and charge separation
• Grantee: Thiago Branquinho de Queiroz
• Support Opportunities: Research Grants - Young Investigators Grants
• FAPESP's process: 24/02191-2 - Low bandgap and donor-acceptor molecular systems as described by a hybrid functional with local range separation
• Grantee: Reinaldo Vieira Dantas Filho
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)