Constrained self-consistent field method revisited toward theoretical designs of functional materials under external field

This Letter explores the potential utility of the constrained self-consistent field (CSCF) method as an efficient methodology for estimating the external fields that reproduce desired physical quantities. Using the fact that a Lagrange multiplier introduced in CSCF corresponds to an external field (perturbation), numerical assessments of CSCF were carried out on the benzene molecule. The activation energies and critical electric fields that reverse the polarizations of the ferroelectric material tetrathiafulvalene-p-chloranil (TTF-CA) were efficiently estimated. The numerical assessments demonstrate the potential applicability of CSCF for the practical designs of materials possessing certain desired physical quantities induced by external fields.