In several limits of approximation, an efficient low-scaling hierarchy of coupled cluster (CC) electronic structure methods has been established, such as the alternatives within the framework of projected atomic orbitals, orbital-specific-virtual (OSV), pair-nature-orbital (PNO) and so on. These methods have been demonstrated to often achieve chemical accuracy with significantly reduced CC computational cost by orders of magnitude, and applied to treat systems containing hundreds of atoms as well as condensed materials. The success of these high-level low-scaling electronic structure methods in computing molecular static properties opens up a new perspective for us to think in new ways to compute molecular dynamical properties by making similar efficiency and accuracy to those of static calculations. Along this line, we are developing an algorithm to compute the explicit analytical gradients towards the OSV-based hierarchy of energy functionals, starting with the second-order Møller Plesset perturbation (OSV-MP2) method. Here we consider the explicit relaxation of perturbed OSV orbitals that are required to be the eigenvectors of the perturbed MP2 diagonal amplitudes. In this presentation, we will have a discussion on (1) the algorithm and implementation with an analysis of formal computing complexity, (2) formal issues and properties of both OSV and hybrid PNO orbital response vectors, (3) the numerical assessment of OSV-MP2 structure optimization for a test set of molecules, and (4) a proof-of-principle demonstration of the low-scaling ab-initio molecular dynamics simulation driven by OSV-MP2 forces.
Jun Yang is an assistant professor of Department of Chemistry of The University of Hong Kong. He received his Ph.D. from Institut für Theoretische Chemie, Universität zu Köln in 2007, under the direction of Prof. Michael Dolg. After doing postdoctoral research with Prof. Garnet Chan at Cornell University and at Princeton University, he became a lecturer of Department of Chemistry of Princeton University in 2013. He then moved to Hong Kong and joined the HKU faculty in 2016. Jun Yang has published many important papers, including 1 in Science. He has also received numerous awards, inlcudings the Early Career Scheme Award from The Research Grants Council of Hong Kong, the IBM-Löwdin Award from the 50th Sanibel Symposium, and the DFG SPP1145 Research Fellow from Deutsche Forschungsgemeinschaft, Germany.