Computational chemistry simulations are extensively used to model natural phenomena. To maintain performance similar to molecular mechanics, but achieve comparable accuracy to quantum mechanical calculations, many researchers are using hybrid QM/MM methods. In this article we evaluate our GPU-accelerated ONIOM implementation by measurements on the crambin and HIV integrase proteins with different size QM model systems. We demonstrate that by using a larger QM region, a better energy accuracy can be achieved at the expense of simulation time. This trade-off is important to consider for the researcher running QM/MM calculations. Furthermore, we show that the ONIOM energy monotonically approaches the pure quantum mechanical energy of the whole system. The experiments are made feasible by utilizing the cutting-edge BrianQC quantum chemistry module for Hartree-Fock level SCF and our GPU-accelerated MMFF94 force field implementation for molecular mechanics calculations.

计算化学模拟被广泛用于模拟自然现象。为了保持类似于分子力学的性能，但达到与量子力学计算相当的精度，许多研究人员正在使用混合QM / MM方法。在本文中，我们通过使用不同大小的QM模型系统对Crambin和HIV整合酶蛋白进行测量，评估了GPU加速的ONIOM实施。我们证明，通过使用更大的QM区域，可以以牺牲仿真时间为代价实现更好的能量精度。对于运行QM / MM计算的研究人员来说，这一折衷很重要。此外，我们表明ONIOM能量单调接近整个系统的纯量子机械能。