Prentice Andrew W, Coe Jeremy P, Paterson Martin J
Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K.
J Chem Theory Comput. 2023 Dec 26;19(24):9161-9176. doi: 10.1021/acs.jctc.3c00897. Epub 2023 Dec 7.
A modular selected configuration interaction (SCI) code has been developed that is based on the existing Monte-Carlo configuration interaction code (MCCI). The modularity allows various selection protocols to be implemented with ease and allows for fair comparison between wave functions built via different criteria. We have initially implemented adaptations of existing SCI theories, which are based on either energy- or coefficient-driven selection schemes. These codes have been implemented not only in the basis of Slater determinants (SDs) but also in the basis of configuration state functions (CSFs) and extended to state-averaged regimes. This allows one to take advantage of the reduced dimensionality of the wave function in the CSF basis and also the guarantee of pure spin states. All SCI methods were found to be able to predict potential energy surfaces to high accuracy, producing compact wave functions, when compared to full configuration interaction (FCI) for a variety of bond-breaking potential energy surfaces. The compactness of the error-controlled adaptive configuration interaction approach, particularly in the CSF basis, was apparent with nonparallelity errors within chemical accuracy while containing as little as 0.02% of the FCI CSF space. The size-to-accuracy was also extended to FCI spaces approaching one billion configurations.
基于现有的蒙特卡罗组态相互作用代码（MCCI），开发了一种模块化的选定组态相互作用（SCI）代码。模块化使得各种选择协议能够轻松实现，并允许对通过不同标准构建的波函数进行公平比较。我们最初实现了对现有SCI理论的改编，这些理论基于能量驱动或系数驱动的选择方案。这些代码不仅在斯莱特行列式（SDs）的基础上实现，也在组态态函数（CSFs）的基础上实现，并扩展到态平均体系。这使得人们能够利用CSF基中波函数维度的降低以及纯自旋态的保证。与全组态相互作用（FCI）相比，对于各种断键势能面，发现所有SCI方法都能够高精度地预测势能面，产生紧凑的波函数。误差控制的自适应组态相互作用方法的紧凑性，特别是在CSF基中，在化学精度内的非平行性误差中很明显，同时只包含FCI CSF空间的0.02%。尺寸与精度的关系也扩展到接近十亿个组态的FCI空间。
