Robust ?SCF calculations with direct energy functional minimization methods and STEP for molecules and materials

The direct energy functional minimization method using the orbital transformation (OT) scheme in the program package CP2K has been employed for delta self-consistent field (delta SCF) calculations. The OT method for non-uniform molecular orbitals occupations allows us to apply the delta SCF method for various kinds of molecules and periodic systems. Vertical excitation energies of heteroaromatic molecules and condensed phase systems, such as solvated ethylene and solvated uracil obeying periodic boundary conditions, are reported using the delta SCF method. In addition, a Re-phosphate molecule attached to the surface of anatase (TiO2) has been investigated. Additionally, we have implemented a recently proposed state-targeted energy projection delta SCF algorithm [K. Carter-Fenk and J. M. Herbert, J. Chem. Theory Comput. 16(8), 5067-5082 (2020)] for diagonalization based SCF in CP2K. It is found that the OT scheme provides a smooth and robust SCF convergence for all investigated excitation energies and (non-)periodic systems. Published under an exclusive license by AIP Publishing.

Automated summary

In this study, the direct energy functional minimization method using the orbital transformation (OT) scheme in the program package CP2K was employed to investigate the delta self-consistent field (delta SCF) method. The results showed that the OT scheme provides a smooth and robust SCF convergence for all investigated excitation energies and (non-)periodic systems.