Ground-state density-matrix algorithm for excited-state adiabatic surfaces: application to polyenes

A low-cost method for computing excited-state adiabatic surfaces, which tot ally avoids the calculation of the excited-state many-electron wavefunction s, and scales favorably with molecular size is proposed. The technique comb ines standard ground-state calculations with a time-dependent density-matri x calculation of vertical optical excitations, using the ground-state singl e-electron density matrix as an input. Several surfaces are generated simul taneously. The structure and vibrational frequencies of the B-1(u) state of hexatriene and octatetraene are calculated using this method. The computed sign of the excited-state equilibrium displacements facilitates rapid anal ysis of resonance Raman measurements. (C) 1999 Elsevier Science B.V. All ri ghts reserved.