Assessing the performance of density functional theory for the dynamic polarizabilities of amino acids: Treatment of correlation and role of exact exchange

The theoretical determination of electric response properties of the biological systems is a field where the application of density functional theory (DFT) appears to be quite promising. In this work, the performance of 41 density functional methods is evaluated in predicting dynamic polarizabilities of an experimental benchmark set of 20 proteinogenic amino acids. The behavior of a large number of density functionals, including various types of the local spin density approximation (LSDA), generalized gradient approximation (GGA), meta-GGA (m-GGA), hybrid-GGA (h-GGA), hybrid meta-GGA (hm-GGA), and range-separated hybrid-GGA (rsh-GGA), has been assessed for the purpose. Analyzing the results of our DFT benchmarking, we found that these computationally economical methods show very diverse predictive capability and a careful selection of DFT functionals is very important in the polarizability calculations. Considering the role of exchange, correlation, dispersion and long-range corrections, it turned out that in the LSDA class, SVWN3 gives better results than SPL and SVWN5 toward the reference values. Of the GGA methods, OPBE outperforms all other functionals. The M06-L is the best method of m-GGA class. The B3LYP and TPSSh are the best functionals of h-GGA and hm-GGA lineages, respectively. Finally, CAM-B3LYP is the best method of rsh-GGA functionals that predicts the most accurate polarizability for amino acids by a large margin with respect to others. Overall, the best performing functionals turn out to be hm-GGAs TPSSh, TPSS1KCIS, M05, tau-HCTHhyb, and h-GGA B3LYP. Hopefully, the results of this investigation might provide the useful guidance to propose a new exchange-correlation functional for calculating the optical properties of biomolecular materials. (c) 2013 Wiley Periodicals, Inc.