Atoms-In-a-Molecule-In-a High Intensity LASER: Dynamical Molecular Electron Densities

Abstract

Abstract Current technologies in optics have grown to an extent where experiments are conducted on molecules in high intensity (∼ 10 14 − 10 16 W/cm 2 ) and high-frequency LASER pulses in the timescales of femtoseconds (10 −15 s) to attoseconds (10 −18 s). These are the timescales where electronic motion happens, and the electric field intensities are much more significant than an atom’s internal field strength (∼ 10 3 W/cm 2 ). Thus, specific frequency-tuned LASERs were used to gauge and control the dynamics of atoms and elec- trons in molecules. In the same context, time-resolved X-ray diffraction laser pulses have been studied for time-evolving electronic charge distributions. Using theoretical methods, obtaining the time-dependent wave function of atoms and molecules in external LASER fields became possible through the parallel development of theoretical methodologies. Therefore, this has en- abled researchers to evaluate molecular densities and retrieve the electronic properties of atoms and molecules in the presence of external time-evolving fields. This thesis attempts to study the dynamics of molecular electron densi- ties through their time-varying topographies, bond paths, zero-flux surfaces, and Atoms-In-a-Molecule properties in a LASER. Thus, Chapter 1 introduces the basics of the electronic structure of atoms and molecules, the standard solutions of time-independent and time-dependent Schrödinger equations to obtain the wave functions essential to evaluate electron densities and proper- ties. The topological tools, such as gradient paths, critical points, bond paths, zero-flux surfaces, and Bader’s quantum theory of Atoms-In-Molecules, are briefly explained, which will help understand features in the time-evolving electron density distributions. The final section of this chapter describes the plan for the thesis.