Semiclassical on-the-fly computation of the S(0)-->S(1) absorption spectrum of formaldehyde.
The anharmonic S(0)-->S(1) vibronic absorption spectrum of the formaldehyde molecule is computed on the fly using semiclassical dynamics. This first example of an on-the-fly semiclassical computation of a vibronic spectrum was achieved using a unit prefactor modified frozen Gaussian semiclassical propagator for the excited state. A sample of 6000 trajectories sufficed for obtaining a converged spectrum, which is in reasonable agreement with experiment. Similar agreement is not obtained when using a harmonic approximation for the spectrum, demonstrating the need for a full anharmonic computation. This first example provides a resolution of approximately 100 cm(-1). Potential ways of improving the methodology and obtaining higher resolution and accuracy are discussed.
Tatchen
Jörg
J
Department of Chemical Physics, Weizmann Institute of Science, 76100 Rehovot, Israel. joerg.tatchen@weizmann.ac.il
Pollak
Eli
E
D000042:Absorption; D000818:Animals; D019295:Computational Biology; D003198:Computer Simulation; D004175:Diptera; D005557:Formaldehyde / Q000737:chemistry*; D008956:Models, Chemical; D015394:Molecular Structure; D011789:Quantum Theory; D013816:Thermodynamics
D005557:Formaldehyde