Extreme Scalability of DFT-based QM/MM MD Simulations Using MiMiC
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AuthorBolnykh, Viacheslav; Olsen, Jógvan Magnus Haugaard; Meloni, Simone; Bircher, Martin Peter; Ippoliti, Emiliano; Carloni, Paolo; Rothlisberger, Ursula
We present a highly scalable DFT-based QM/MM implementation developed within MiMiC, a recently introduced multiscale modeling framework that uses a loose-coupling strategy in conjunction with a multiple-program multiple-data (MPMD) approach. The computation of electrostatic QM/MM interactions is parallelized exploiting both distributed- and shared-memory strategies. Here, we use the efficient CPMD and GROMACS programs as QM and MM engines, respectively. The scalability is demonstrated through large-scale benchmark simulations of realistic biomolecular systems employing GGA and hybrid exchange-correlation functionals. We show that the loose-coupling strategy adopted in MiMiC, with its inherent high flexibility, does not carry any significant computational overhead compared to a tight-coupling scheme. Furthermore, we demonstrate that the adopted parallelization strategy enables scaling of up to 13,000 CPU cores with efficiency above 70%, thus making DFT-based QM/MM MD simulations using hybrid functionals at the nanosecond scale accessible.
Accepted manuscript version. Published version in Journal of Chemical Theory and Computation available at https://doi.org/10.1021/acs.jctc.9b00424.