AN EFFICIENT IMPLEMENTATION OF TIME-DEPENDENT DENSITY-FUNCTIONAL THEORY FOR THE CALCULATION OF EXCITATION-ENERGIES OF LARGE MOLECULES

Time-dependent density-functional (TDDFT) methods are applied within t he adiabatic approximation to a series of molecules including C-70. OU T implementation provides an efficient approach for treating frequency -dependent response properties and electronic excitation spectra of la rge molecules. We also present a new algorithm for the diagonalization of large non-Hermitian matrices which is needed for hybrid functional s and is also faster than the widely used Davidson algorithm when empl oyed for the Hermitian case appearing in excited energy calculations. Results for a few selected molecules using local, gradient-corrected, and hybrid functionals are discussed. We find that for molecules with low lying excited states TDDFT constitutes a considerable improvement over Hartree-Fock based methods (like the random phase approximation) which require comparable computational effort. (C) 1998 American Insti tute of Physics. [S0021-9606(98)30643-1].