Lischka Hans, Shepard Ron, Müller Thomas, Szalay Péter G, Pitzer Russell M, Aquino Adelia J A, Araújo do Nascimento Mayzza M, Barbatti Mario, Belcher Lachlan T, Blaudeau Jean-Philippe, Borges Itamar, Brozell Scott R, Carter Emily A, Das Anita, Gidofalvi Gergely, González Leticia, Hase William L, Kedziora Gary, Kertesz Miklos, Kossoski Fábris, Machado Francisco B C, Matsika Spiridoula, do Monte Silmar A, Nachtigallová Dana, Nieman Reed, Oppel Markus, Parish Carol A, Plasser Felix, Spada Rene F K, Stahlberg Eric A, Ventura Elizete, Yarkony David R, Zhang Zhiyong
Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, USA.
Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, USA.
J Chem Phys. 2020 Apr 7;152(13):134110. doi: 10.1063/1.5144267.
The core part of the program system COLUMBUS allows highly efficient calculations using variational multireference (MR) methods in the framework of configuration interaction with single and double excitations (MR-CISD) and averaged quadratic coupled-cluster calculations (MR-AQCC), based on uncontracted sets of configurations and the graphical unitary group approach (GUGA). The availability of analytic MR-CISD and MR-AQCC energy gradients and analytic nonadiabatic couplings for MR-CISD enables exciting applications including, e.g., investigations of π-conjugated biradicaloid compounds, calculations of multitudes of excited states, development of diabatization procedures, and furnishing the electronic structure information for on-the-fly surface nonadiabatic dynamics. With fully variational uncontracted spin-orbit MRCI, COLUMBUS provides a unique possibility of performing high-level calculations on compounds containing heavy atoms up to lanthanides and actinides. Crucial for carrying out all of these calculations effectively is the availability of an efficient parallel code for the CI step. Configuration spaces of several billion in size now can be treated quite routinely on standard parallel computer clusters. Emerging developments in COLUMBUS, including the all configuration mean energy multiconfiguration self-consistent field method and the graphically contracted function method, promise to allow practically unlimited configuration space dimensions. Spin density based on the GUGA approach, analytic spin-orbit energy gradients, possibilities for local electron correlation MR calculations, development of general interfaces for nonadiabatic dynamics, and MRCI linear vibronic coupling models conclude this overview.
程序系统COLUMBUS的核心部分允许在单双激发组态相互作用（MR-CISD）和平均二次耦合簇计算（MR-AQCC）的框架内，基于未收缩的组态集和图形酉群方法（GUGA），使用变分多参考（MR）方法进行高效计算。MR-CISD的解析能量梯度和解析非绝热耦合的可用性使得包括例如对π共轭双自由基化合物的研究、大量激发态的计算、 diabatic化程序的开发以及为实时表面非绝热动力学提供电子结构信息等令人兴奋的应用成为可能。通过完全变分的未收缩自旋轨道MRCI，COLUMBUS为对包含重原子直至镧系和锕系元素的化合物进行高水平计算提供了独特的可能性。有效执行所有这些计算的关键是CI步骤要有高效的并行代码。现在，在标准并行计算机集群上，可以相当常规地处理大小为数十亿的组态空间。COLUMBUS的新进展，包括全组态平均能量多组态自洽场方法和图形收缩函数方法，有望允许实际上无限的组态空间维度。基于GUGA方法的自旋密度、解析自旋轨道能量梯度、局部电子相关MR计算的可能性、非绝热动力学通用接口的开发以及MRCI线性振子耦合模型构成了本综述的内容。
