Electronic temperature in divide-and-conquer electronic structure calculation revisited: Assessment and improvement of self-consistent field convergence

We investigated the electronic temperature dependence of divide-and-conquer (DC) self-consistent field (SCF) method in calculations of uniform (U) and bond-alternating polyene chains. It was found that part of total energy error of DC calculation is caused by a finite electronic temperature appeared in the DC formalism. As the electronic temperature decreases, the error by the finite temperature decreases to zero but the number of SCF iteration increases, especially in the U chain calculation. To improve the DC SCF convergence with a high energy accuracy, we introduced the temperature-lowering technique into DC calculation. Numerical assessment reveals the good performance of the present method.