We revisit the formalism for analytic derivative couplings between excited states in time-dependent density functional theory (TDDFT). We derive and implement these couplings using quadratic response theory, then numerically compare this response-theory formulation to couplings implemented previously based on a pseudo-wavefunction formalism and direct differentiation of the Kohn-Sham determinan...

We report calculations of core excitation energies and near-edge X-ray absorption fine structure (NEXAFS) spectra computed with time-dependent density functional theory (TDDFT). TDDFT with generalized gradient approximation and standard hybrid exchange-correlation functionals is known to underestimate core excitation energies. This failure is shown to be associated with the self-interaction err...

Most applications of time-dependent density-functional theory (TDDFT) use the adiabatic local-density approximation (ALDA) for the dynamical exchange-correlation potential V(xc)(r,t). An exact (i.e., nonadiabatic) extension of the ground-state LDA into the dynamical regime leads to a V(xc)(r,t) with a memory, which causes the electron dynamics to become dissipative. To illustrate and explain th...

We have theoretically characterized the ground state and the excited state properties of wybutine, a naturally fluorescent modified base occuring in tRNAs, using configuration interaction singles (CIS) and time dependent density functional (TDDFT) methods. Both gas phase excited state properties and solvent effects, modelled through Onsager reaction field method, were considered. In addition to...

We present time-dependent density functional theory (TDDFT) calculations for single and dimerized Coumarin-343 molecules to investigate the quantum mechanical effects of chromophore aggregation in extended systems designed to function as a new generation of sensors and light-harvesting devices. Using the single-chromophore results, we describe the construction of effective Hamiltonians to predi...

Plasmonic catalysis provides a possible means for driving chemical reactions under relatively mild conditions. Rational design of these systems is impeded by the difficulty in understanding electron dynamics and their interplay with reactions. Real-time, time-dependent density functional theory (RT-TDDFT) can provide dynamic information on excited states plasmonic systems, including those relev...

The availability of X-ray light sources with increased resolution and intensity has provided a foundation for increasingly sophisticated experimental studies exploiting the spectroscopy core electrons to probe fundamental chemical, physical, biological processes. Quantum chemical calculations can play critical role in analysis these measurements. relatively low computational cost density functi...

The combined time-dependent density functional theory effective fragment potential method (TDDFT/EFP1) is applied to a study of the solvent-induced shift of the lowest singlet π → π* charge-transfer excited state of p-nitroaniline (pNA) from the gas to the condensed phase in water. Molecular dynamics simulations of pNA with 150 EFP1 water molecules are used to model the condensed-phase and gene...

Density functional theory is now the method of choice for calculating the electronic structure of complex systems, and time-dependent density functional theory (TDDFT) is now the preferred method for calculating spectroscopic properties of large molecules. The validity of the theory depends mainly on the quality of the approximation to the unknown exchange-correlation energy. In the present pap...

The van der Waals dispersion coefficients of a set of polycyclic aromatic hydrocarbons, ranging in size from the single-cycle benzene to circumovalene (C(66)H(20)), are calculated with a real-time propagation approach to time-dependent density functional theory (TDDFT). In the nonretarded regime, the Casimir-Polder integral is employed to obtain C(6), once the dynamic polarizabilities have been...