Divide‐And‐Conquer Extended Tight‐Binding Molecular Dynamics: A General‐Purpose, Very Large‐Scale Quantum Molecular Dynamics Method

We have combined the linear-scaling divide-and-conquer (DC) method with the semi-empirical extended tight-binding (xTB) method to develop a general-purpose large-scale quantum molecular dynamics simulation platform called DCxTBMD. Although the DC method is a fragmentation-based acceleration scheme, it is possible to perform highly accurate calculations even when adopting formal grid-based fragmentation, thanks to the mechanism called the buffer region. The program was developed by incorporating xTB Hamiltonian construction modules in the xTB program into the DCDFTBK package, a DC-based density functional tight-binding (DFTB) calculation suite. The accuracy and computational time, including the parallel scalability, of the present method were investigated on the Japanese supercomputer Fugaku, and it was found that the present method is suitable for the efficient calculation of large systems, including multiple heteroelements. We further implemented the energy gradient of the present method to enable the molecular dynamics simulation of such systems.