An alternative to the "Star Path" enhancement of the ADMA linear scaling method for protein modeling

With the aim of improving the performance of macromolecular quantum chemistry conformation analysis and reaction path following methods, the Adjustable Density Matrix Assembler (ADMA) method has already been combined with some faster although less accurate density matrix extrapolation methods, such as the Löwdin-Inverse-Löwdin (LIL) extrapolation along a potential energy surface, and a strategically arranged back-and-forth switching between these methods has been proven to be advantageous. Here, an alternative approach is proposed and investigated, based on several actual test calculations, where the "inexpensive" LIL density matrix extrapolation steps are replaced by only somewhat more expensive, but still ADMA-based calculations, where in the "rough-search stage," only interactions of shorter distances within the macromolecule are considered. It is shown that this approach is viable, as an alternative to the "Star Path" method including both ADMA and LIL steps. © 2017 Wiley Periodicals, Inc.