Fully Atomistic Real-Time Simulations of Transient Absorption Spectroscopy

BONAFÉ, FRANCO P.; HERNÁNDEZ, FEDERICO J.; ARADI, BÁLINT; FRAUENHEIM, THOMAS; CRISTIAN GABRIEL SANCHEZ

Cartagena de Indias

Encuentro; THE 10TH INTERNATIONAL MEETING ON PHOTODYNAMICS AND RELATED ASPECTS; 2018

Universidad de Antioquía y Universidad Nacional de Colombia

We have implemented an electron-nuclear real-time propagation scheme for the calculation of transient absorption spectra within the framework of the Time Dependent Density Functional Tight Binding electronic structure method. When this technique is applied to the study of ultrafast dynamics of Soret-excited zinc(II)-tetraphenylporphyrin in the sub- picosecond time scale, quantum beats in the transient absorption caused by impulsively excited molecular vibrations are observed. The launching mechanism of such vibrations can be regarded as a displacive excitation of the zinc-pyrrole and pyrrole C-C bonds (1). In this talk we will describe the implementation and results related to Zn-TPP and other systems.Figure 1. a) Absorption spectrum of Zn-TPP. b) & d) TAS of Zn-TPP from a 10 fs pump pulse centered at 450 nm with moving and frozen nuclei. c) & d) Fourier transform on the delay time, vibratuinal signatures of impulsively excited vibrational modes can be observed.