We want to simulate external forces by the appication of geometry constraints. This “COnstraint GEometry to simulate Forces” is known as the COGEF method [Beyer2000].
Beyer, M. K. J. Chem. Phys. 112 (2000) 7307
Brügner, O.; Walter, M. Phys. Rev. Materials 2 (2018) 113603