As a general tool for analysis of chemical reactions from the view point of electron wavepacket dynamics, electron flux within a molecule is numerically realized in terms of physically time-dependent electronic wavefunctions given by the semiclassical Ehrenfest theory. These wavefunctions are synchronized with real time motion of molecular nuclei through the nuclear kinematic coupling (nonadiabatic elements). Since the standard quantum flux gives only a nullfield for a real-valued electronic eigenfunction, we extend the definition of flux such that the essential information of dynamical flow of electrons can be retrieved even from adiabatic electronic wavefunctions calculated in the scheme of the so-called ab initio molecular dynamics. (C) 2009 Elsevier B.V. All rights reserved.