Robust Convergence of Self-Consistent-Field-Methods
One of our ongoing projects is the development of robust second-order methods for converging self-consistent field methods as HF, DFT, and CASSCF. In our recent work, we exploit the full electronic (augmented) Hessian (AH) in combination with trust-region (TR) methods to converge SCF energy calculations of molecules and clusters with a complicated electronic structure. For such systems, the standard direct inversion of the iterative subspace (DIIS) approach is problematic while our TRAH-SCF implementation in ORCA converges smoothly and reliably towards a local minimum. TRAH-SCF currently works for restricted and unrestricted HF and DFT and we plan to extend the approach to various MR methods.
B. Helmich-Paris; A trust-region augmented Hessian implementation for restricted and unrestricted Hartree–Fock and Kohn–Sham methods, J. Chem. Phys. 154, 164104 (2021). https://doi.org/10.1063/5.0040798