Prochnow Eric, Harding Michael E, Gauss Jürgen
Institut für Physikalische Chemie, Universität Mainz, D-55099 Mainz, Germany.
J Chem Theory Comput. 2010 Aug 10;6(8):2339-47. doi: 10.1021/ct1002016.
A scheme for the parallel calculation of energies at the coupled-cluster singles, doubles, and triples (CCSDT) level of theory, several approximate iterative CCSDT schemes (CCSDT-1a, CCSDT-1b, CCSDT-2, CCSDT-3, and CC3), and for the state-specific multireference coupled-cluster ansatz suggested by Mukherjee with a full treatment of triple excitations (Mk-MRCCSDT) is presented. The proposed scheme is based on the adaptation of a highly efficient serial coupled-cluster code leading to a communication-minimized implementation by parallelizing the time-determining steps. The parallel algorithm is tailored for affordable cluster architectures connected by standard communication networks such as Gigabit Ethernet. In this way, CCSDT and Mk-MRCCSDT computations become feasible even for larger molecular systems and basis sets. An analysis of the time-determining steps for CCSDT and Mk-MRCCSDT, namely the computation of the triple-excitation amplitudes and their individual contributions, is carried out. Benchmark calculations are presented for the N2O, ozone, and benzene molecules, proving that the parallelization of these steps is sufficient to obtain an efficient parallel scheme. A first application to the case of 2,6-pyridyne using a triple-ζ quality basis (222 basis functions) is presented demonstrating the efficiency of the current implementation.
提出了一种用于在耦合簇单、双、三激发（CCSDT）理论水平上并行计算能量的方案，以及几种近似迭代CCSDT方案（CCSDT - 1a、CCSDT - 1b、CCSDT - 2、CCSDT - 3和CC3），还提出了针对Mukherjee建议的具有三激发全处理的态特定多参考耦合簇假设（Mk - MRCCSDT）的方案。所提出的方案基于对高效串行耦合簇代码的改编，通过并行化时间决定步骤实现通信最小化。该并行算法是为通过诸如千兆以太网等标准通信网络连接的经济适用的集群架构量身定制的。通过这种方式，即使对于更大的分子系统和基组，CCSDT和Mk - MRCCSDT计算也变得可行。对CCSDT和Mk - MRCCSDT的时间决定步骤进行了分析，即三激发振幅及其各自贡献的计算。给出了N₂O、臭氧和苯分子的基准计算结果，证明这些步骤的并行化足以获得高效的并行方案。展示了首次使用三重ζ质量基（222个基函数）对2,6 - 吡啶炔的应用，证明了当前实现的效率。
