Approaching black-box calculations of pump-probe fragmentation dynamics of polyatomic molecules

Abstract

<jats:title>Abstract</jats:title><jats:p>A general framework for the simulation of ultrafast pump-probe time resolved experiments based on Born-Oppenheimer molecular dynamics (BOMD) is presented. Interaction of the molecular species with a laser is treated by a simple maximum entropy distribution of the excited state occupancies. The latter decay of the electronic excitation into the vibrations is based on an on-the-fly estimation of the rate of the internal conversion, while the energy is distributed in a thermostat-like fashion. The approach was tested by reproducing the results of previous femtosecond studies on ethylene, naphthalene and new results for phenanthrene.</jats:p>

Roadmap on dynamics of molecules and clusters in the gas phase

“…Successful interpretation of the interplay between ionization and fragmentation channels in these complex system relies on the simultaneous analysis of multiple data sets, including TOF-MS and electronic and ionic VMI images. The analysis was supported by theoretical modeling [21], and it was found that phenanthrene (C 14 H 10 ) undergoes several ionization steps as well as fragmentation. Based on covariance analysis, Coulomb explosion leads to the fragmentation of…”

“…The most popular methods which focus on chemical responses at the fs timescale include trajectory surface hopping molecular dynamics (TSH MD), ab initio multiple spawning (AIMS) and multiconfigurational time-dependent Hartree (MCTDH) (see citations in Ref. [21]). They provide a treatment of the nuclear motions within several electronic states, but calculations of this nature are very computationally demanding (see Sect.…”

“…with n = 2, 3, 4 [21]. Figure 3 shows the experimental and theoretical ion yields for the dication and C 2 H + x fragment.…”

“…The transient peaks at t ∼ t 0 are a signatures of short-lived intermediates. By modeling and experimental analysis, we attribute these intermediates to the PAH molecular/ionic excited states [21].…”

“…The data and theoretical treatment were first presented in Ref. [21] setups are becoming more and more keen on combining multiple techniques for providing full insight into the systems of study. Parallel to these efforts, theoretical methods should become less computationally expensive and more accurate to provide a valid explanation of the processes observed in experiments.…”