[GS_C_MS] A direct minimization framework for charged-supercell electronic structure calculations
ABSTRACT
We implement a Born–Oppenheimer direct-minimization solver in Quantum ESPRESSO for charged-supercell electronic-structure calculations. The solver minimizes the Kohn–Sham total-energy functional directly with respect to the electronic orbitals, replacing the conventional diagonalization-based self-consistent-field (SCF) procedure with an orbital-optimization approach under orthonormality constraints. We validate the implementation by applying it to semilocal exchange-correlation functionals and comparing the resulting total energies with those from SCF calculations using Davidson diagonalization. The direct-minimization solver reproduces the reference SCF energies, demonstrating the consistency of the orbital minimization, density reconstruction, and total-energy evaluation. This establishes a computational framework for charged-supercell calculations based on direct variational minimization and provides a basis for future extensions to constrained minimization schemes.
