Accurate Molecular Nonlinear Properties on a Semiempirical Budget Using the TDDFT-ris Model

High Resolution Image Download MS PowerPoint Slide Time-Dependent Density Functional Theory (TDDFT) is a workhorse computational tool for predicting nonlinear optical properties from first principles. However, its computational cost often limits its practicality for large molecules. We evaluate nonlinear response properties using our recently developed semiempirical model, TDDFT-ris (ris), and its extension, TDDFT-risp (risp), which use minimal auxiliary basis to approximate electron-repulsion integrals. Against full TDDFT with def2-SVPD calculations, ris and risp accurately reproduce (hyper)polarizabilities for a small fraction of the computational cost. For example, ris has a mean relative error of 8% when computing mean polarizabilities, which is reduced to 2% by risp. Furthermore, the strong physical justification for the risp method allows us to cure systematic failures in monopole-based semiempirical models (like ris) when computing nonlinear properties of planar molecules. Thus, ris and risp are powerful and inexpensive tools for predicting nonlinear optical properties either qualitatively or nearly quantitatively.