Time-Dependent Extension of Grimme's Continuous Chirality Measure for Electronic Chirality Flips in Femto- and Attosecond Time Domains.

ABSTRACT

Grimme's Continuous Chirality Measure ( C C M ${CCM}$ ) was developed for comparisons of the chirality of the electronic wave functions of molecules, typically in their ground states. For example, C C M = 14 . 5 ${CCM=14.5}$ , 1 . 2 ${1.2}$ and 0 . 0 ${0.0}$ for alanine, hydrogen-peroxide, and for achiral molecules, respectively. Well-designed laser pulses can excite achiral molecules from the electronic ground state to time-dependent chiral superposition states, with chirality flips in the femto- or even attosecond (fs or as) time domains. Here we provide a time-dependent extension C C M t ${CCM\left(t\right)}$ of Grimme's C C M ${CCM}$ for trailing the electronic chirality flips. As examples, we consider two laser driven electronic wavefunctions which represent flips between opposite electronic enantiomers of oriented NaK within 4 . 76 f s ${4.76\ {\rm f}{\rm s}}$ and 433 a s ${433\ {\rm a}{\rm s}}$ . The corresponding C C M t ${CCM\left(t\right)}$ vary respectively from 14 . 5 ${14.5}$ or from 13 . 3 ${13.3}$ to 0 . 0 ${0.0}$ , and back.