title: Ab Initio Finite-Temperature Electronic Absorption Spectrum of Formamide.
abstract: A combination of Car-Parrinello molecular dynamics (CP-MD) and high-level ab initio quantum chemical calculations has been used to calculate the electronic absorption spectrum of formamide at finite temperatures. Thermally broadened spectra have been obtained by averaging over a large number of single-point multireference configuration interaction excitation energies calculated for geometries sampled from a CP-MD simulation. Electronic excitation spectra of possible contaminants ammonia and formamidic acid have also been computed. Ammonia exhibits a strong peak in the shoulder region of the experimental formamide spectrum at 6.5 eV, and formamidic acid has a strong absorption above 7.5 eV. The calculations reproduce the shape of the experimental absorption spectrum, in particular, the low-energy shoulder of the main peak, and demonstrate how finite-temperature electronic absorption spectra can be computed from first principles.
authors.affiliation: School of Chemistry, University of Nottingham, Nottingham, NG7 2RD, United Kingdom, and Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, Bochum, D-44780 Germany.
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Besley
authors.affiliation: School of Chemistry, University of Nottingham, Nottingham, NG7 2RD, United Kingdom, and Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, Bochum, D-44780 Germany.
authors.forename: Nikos L
authors.initials: NL
authors.lastname: Doltsinis