Accelerating Wave Function Convergence in Interactive Quantum Chemical Reactivity Studies

The
inherently high computational cost of iterative self-consistent
field (SCF) methods proves to be a critical issue delaying visual
and haptic feedback in real-time quantum chemistry. In this work,
we introduce two schemes for SCF acceleration. They provide a guess
for the initial density matrix of the SCF procedure generated by extrapolation
techniques. SCF optimizations then converge in fewer iterations, which
decreases the execution time of the SCF optimization procedure. To
benchmark the proposed propagation schemes, we developed a test bed
for performing quantum chemical calculations on sequences of molecular
structures mimicking real-time quantum chemical explorations. Explorations
of a set of six model reactions employing the semi-empirical methods
PM6 and DFTB3 in this testing environment showed that the proposed
propagation schemes achieved speedups of up to 30% as a consequence
of a reduced number of SCF iterations.