Journal Article Research Support, U.S. Gov't, Non-P.H.S. Research Support, U.S. Gov't, P.H.S. Solvents pseudospectral Amino Acids PS-LRC Peptides Proteins Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov't Review TDA TDDFT Tamm-Dancoff approximation barrier height charge transfer number charge-transfer excitation energy density-functional theory electron coupling excitation energy interaction energy nonlinear optical property time-dependent density-functional theory