Photochemistry functional theory, time-dependent

To use direct dynamics for the study of non-adiabatic systems it is necessary to be able to efficiently and accurately calculate electronic wave functions for excited states. In recent years, density functional theory (DFT) has been gaining ground over traditional Hartree-Fock based SCF calculations for the treatment of the ground state of large molecules. Recent advances mean that so-called time-dependent DFT methods are now also being applied to excited states. Even so, at present, the best general methods for the treatment of the photochemistry of polyatomic organic molecules are MCSCF methods, of which the CASSCF method is particularly powerful. 

As follows from the form of the QM/MM Hamiltonian (Eq. 5.8), any electronic structure method can be used for describing the QM and MM parts of the system. Applications discussed in the following session mainly deal with understanding photochemistry in the condensed phase, with a common choice of the excited state methods from the equation of motion coupled cluster (EOM-CC) family [61-64], time-dependent density functional theory (TD-DFT) [65-66], or configuration interaction (Cl) methods. The MM Hamiltonian is represented by either EFPl or EFP Hamiltonian from Eq. 5.1 or Eq. 5.7. //qm-mm coupling term in the QM/EFPl... 

Abstract We review and further develop the excited state structural analysis (ESSA) which was proposed many years ago [Luzanov AV (1980) Russ Chem Rev 49 1033] for semiempirical models of r r -transitions and which was extended quite recently to the time-dependent density functional theory. Herein we discuss ESSA with some new features (generalized bond orders, similarity measures etc.) and provide additional applications of the ESSA to various topics of spectrochemistry and photochemistry. The illustrations focus primarily on the visualization of electronic transitions by portraying the excitation localization on atoms and molecular fragments and by detaiUng excited state structure using specialized charge transfer numbers. An extension of ESSA to general-type wave functions is briefly considered. 

Wohlgemuth M, Bonacic-Koutecky V, Mitric R (2011) Time-dependent density functional theory excited state nonadiabatic d5mamics combined with quantum mechanital/molecular mechanical approach photrxlynamics of indole in water. J Chem Phys 135 054105 Ben Nun M, Quenneville J, Martinez TJ (2000) Ab initio multiple spawning photochemistry from first principles quantum molecular dynamics. J Phys Chem A 104 5161-5175... 

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