MPI-Batched TBPM: A Distributed-Memory Framework for Large-Scale Quantum Simulations
Zewen Wu, Shengjun Yuan
Abstract
The Tight-Binding Propagation Method (TBPM) is a robust computational framework for large-scale quantum simulations with linear scaling in memory and computational time. Building upon shared-memory implementations, this study presents an MPI-accelerated batched TBPM algorithm to exploit distributed-memory high-performance computing systems through domain decomposition and cross-node parallel execution. The approach distributes both the Hamiltonian matrix and wave function states across multiple nodes, enabling memory aggregation and simultaneous utilization of computational resources throughout clusters. The maximum tractable system size is determined primarily by the number of available supercomputing nodes. The batched processing strategy transforms the computational characteristics by reducing matrix access frequency and enhancing computational intensity by a factor of 64, shifting the algorithm from memory-bound to compute-bound regimes. Comprehensive benchmarks on graphene and twisted bilayer graphene demonstrate substantial speedup and memory scalability improvements. Super-linear speedup is consistently observed across both systems, attributed to superior cache efficiency when local Hamiltonian partitions fit within the Last Level Cache, confirming the efficiency and broad applicability of this MPIbased distributed architecture for ultra-large-scale tight-binding calculations.