Analytical excited state forces for the time-dependent density-functional tight-binding method

作者：Heringer D; Niehaus T A^*; Wanko M; Frauenheim Th

来源：Journal of Computational Chemistry, 2007, 28(16): 2589-2601.

DOI：10.1002/jcc.20697

• time-dependent density functional response theory
• time-dependent density functional theory
• adiabatic excitation energy
• TDDFT
• random phase approximation
• DFTB

An analytical formulation for the geometrical derivatives of excitation energies within the time-dependent density-functional tight-binding (TD-DFTB) method is presented. The derivation is based on the auxiliary functional approach proposed in [Furche and Ahlrichs, J Chem Phys 2002, 117, 7433]. To validate the quality of the potential energy surfaces provided by the method, adiabatic excitation energies, excited state geometries, and harmonic vibrational frequencies were calculated for a test set of molecules in excited states of different symmetry and multiplicity. According to the results, the TD-DFTB scheme surpasses the performance of configuration interaction singles and the random phase approximation but has a lower quality than ab initio time-dependent density-functional theory. As a consequence of the special form of the approximations made in TD-DFTB, the scaling exponent of the method can be reduced to three, similar to the ground state. The low scaling prefactor and the satisfactory accuracy of the method makes TD-DFTB especially suitable for molecular dynamics simulations of dozens of atoms as well as for the computation of luminescence spectra of systems containing hundreds of atoms.

• 出版日期2007-12