Ibele Lea M, Memhood Arshad, Levine Benjamin G, Avagliano Davide
CNRS, Institut de Chimie Physique UMR8000, Université Paris-Saclay, 91405 Orsay, France.
Department of Chemistry, Institute for Advanced Computational Science, Stony Brook, New York 11794, United States.
J Chem Theory Comput. 2024 Sep 4. doi: 10.1021/acs.jctc.4c00855.
We introduce an interface between PySpawn, a simulation package to run ab initio multiple spawning (AIMS) nonadiabatic dynamics, and OpenMolcas, a software package to perform multiconfigurational perturbations theory (CASPT2) electronic structure calculations. Our interface allows us to exploit all the functionalities of the two codes: the modular and efficient Python implementation of the AIMS algorithm and the extensive analysis tools offered by PySpawn, with the cutting-edge implementation of CASPT2 equations in OpenMolcas, including the recently introduced analytical gradients and different flavors. Both are fully open-source and free of charge, making the following implementation unique in the current plethora of software for nonadiabatic dynamics. This represents an important step toward a wider application of AIMS-based nonadiabatic dynamics combined with high-accuracy excited-state calculations. The importance and the need for such an implementation are demonstrated by application to the ultrafast relaxation of fulvene from S to S, which is drastically affected by the potential energy surface on which the nuclear wavepacket is propagated. Additionally, the decay is influenced by the CASPT2 flavor adopted, posing interesting questions in the choice of one over the other and opening the door to deeper studies on the effect of CASPT2 formulations in nonadiabatic dynamics.
我们介绍了PySpawn（一个用于运行从头算多电子激发态非绝热动力学的模拟程序包）与OpenMolcas（一个用于进行多组态微扰理论（CASPT2）电子结构计算的软件包）之间的接口。我们的接口使我们能够利用这两个程序的所有功能：AIMS算法的模块化且高效的Python实现以及PySpawn提供的广泛分析工具，以及OpenMolcas中CASPT2方程的前沿实现，包括最近引入的解析梯度和不同变体。两者均完全开源且免费，使得以下实现方式在当前众多非绝热动力学软件中独树一帜。这代表了朝着更广泛应用基于AIMS的非绝热动力学与高精度激发态计算迈出的重要一步。通过将其应用于富烯从S态到S态的超快弛豫过程，证明了这种实现方式的重要性和必要性，该过程受到核波包传播所在势能面的显著影响。此外，衰减还受到所采用的CASPT2变体的影响，这在选择其中一种变体时引发了有趣的问题，并为深入研究CASPT2公式在非绝热动力学中的作用打开了大门。
