A generalized solid-state nudged elastic band (G-SSNEB) method is presented for
determining reaction pathways of solid–solid transformations involving both atomic and unit-
cell degrees of freedom. We combine atomic and cell degrees of freedom into a unified
description of the crystal structure so that calculated reaction paths are insensitive to the
choice of periodic cell. For the rock-salt to wurtzite transition in CdSe, we demonstrate that
the method is robust for mechanisms dominated either by atomic motion or by unit-cell …