First-principles molecular-dynamics simulation of biphenyl under strong laser pulses by time-dependent density-functional theory

Abstract

The femtosecond laser reaction dynamics of the 3,5-difluoro-3 ,5 -dibromo-biphenyl (DFDBrBPh) molecule is investigated using time-dependent density-functional theory combined with molecular-dynamics (TDDFT-MD) simulation. This work is based on a recent experiment that monitored torsional motion of the DFDBrBPh molecule by femtosecond time-resolved Coulomb explosion imaging [Madsen et al., Phys. Rev. Lett. 102, 073007 (2009)]. The results confirm that the probe pulse triggers a Coulomb explosion and the kick pulse induces the torsional motion of two phenyl rings, using the experimental settings of the lasers. The Coulomb explosion dynamics simulation verifies that the F and Br atoms dissociate to the ion detector while maintaining their initial alignment with respect to the phenyl rings, which is the fundamental basis of Coulomb explosion imaging of molecular torsion. Furthermore, the period and amplitude of the torsional motion obtained by the simulation are consistent with the experimental values. This validates the ability of the TDDFT-MD method to reveal the underlying mechanism of experimentally observed molecular torsional dynamics.

Applying artificial neural networks to coherent control experiments: A theoretical proof of concept

“…[24], and the corresponding mean coherence lengths in the angular dimension are roughly based on a potential-energy surface calculation performed in Ref. [30]. Furthermore, we tuned the amplitude variance parameters of η V (φ d , t ) and η α (φ d , t ) to be as large as possible while still allowing our approach to yield good results, and in Sec.…”

Time-dependent density-functional study of the alignment-dependent ionization of acetylene and ethylene by strong laser pulses

“…TDDFT has been used to study the Coulomb explosion of deuterium [41,42], biomolecules immersed in liquid water [43], water clusters [44], and small hydrocarbon molecules [16]. TDDFT simulations have also been used to describe the electron-ion dynamics of H 2 S [45] and to simulate the Coulomb imaging of biphenyl [46]. The plan of this paper is as follows.…”

Nonadiabatic molecular dynamics simulation of C2H22+ in a strong laser field*

“…[18] To date, TDDFT have been employed to deal with a lot of highly nonlinear phenomena, such as multiphoton ionization, [19] high harmonic generation (HHG) in gases and solids, [20,21] as well as nonadiabatic molecular dynamics simulations. [18] Comparing with the other NAMD methods, such as Tully surface hopping, [22] multi configuration timedependent Hartree (MCTDHF), [23] directly solving TDSE, [24] TDDFT-MD scheme has several advantages: it has favorable system-size scaling, and its efficiency allows calculations on large systems for even picoseconds; besides, TDDFT provides an efficient way to describe the strong laser field assisting electron response (ionization, excitation), which is the key part in this work. This is the reason why we choose TDDFT-MD method in this work.…”