TY - JOUR

T1 - Ab initio quantum dynamical study of the multi-state nonadiabatic photodissociation of pyrrole

AU - Faraji, S.

AU - Vazdar, M.

AU - Reddy, V. Sivaranjana

AU - Eckert-Maksic, M.

AU - Lischka, Hans

AU - Koeppel, H.

PY - 2011/10/21

Y1 - 2011/10/21

N2 - There has been a substantial amount of theoretical investigations on the photodynamics of pyrrole,
often relying on surface hopping techniques or, if fully quantal, confining the study to the lowest
two or three singlet states. In this study we extend ab initio based quantum dynamical investigations
to cover simultaneously the lowest five singlet states, two π − σ* and two π − π* excited
states. The underlying potential energy surfaces are obtained from large-scale MRCI ab initio computations.
These are used to extract linear and quadratic vibronic coupling constants employing the
corresponding coupling models. For the N-H stretching mode Q24 an anharmonic treatment is necessary
and also adopted. The results reveal a sub-picosecond internal conversion from the S4 (π − π*)
state, corresponding to the strongly dipole-allowed transition, to the S1 and S2 (π − σ*) states and,
hence, to the ground state of pyrrole. The significance of the various vibrational modes and coupling
terms is ass

AB - There has been a substantial amount of theoretical investigations on the photodynamics of pyrrole,
often relying on surface hopping techniques or, if fully quantal, confining the study to the lowest
two or three singlet states. In this study we extend ab initio based quantum dynamical investigations
to cover simultaneously the lowest five singlet states, two π − σ* and two π − π* excited
states. The underlying potential energy surfaces are obtained from large-scale MRCI ab initio computations.
These are used to extract linear and quadratic vibronic coupling constants employing the
corresponding coupling models. For the N-H stretching mode Q24 an anharmonic treatment is necessary
and also adopted. The results reveal a sub-picosecond internal conversion from the S4 (π − π*)
state, corresponding to the strongly dipole-allowed transition, to the S1 and S2 (π − σ*) states and,
hence, to the ground state of pyrrole. The significance of the various vibrational modes and coupling
terms is ass

M3 - Article

SP - 154310

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

ER -