标题： 带大活性空间的驱动相似性重正化群：在寡聚烯、玉米黄质和铬二聚体中的应用 显示英文标题

标题： Driven similarity renormalization group with a large active space: Applications to oligoacenes, zeaxanthin, and chromium dimer

摘要： 我们提出了一种基于密度矩阵重正化群（DMRG）参考的驱动相似性重正化群（DSRG）的新实现。 通过形成矩阵乘积态压缩中间体，避免了高阶约化密度矩阵的显式构建。 该算法使得将DSRG二阶和三阶微扰理论应用于具有50个电子在50个轨道中的活性空间的十二烷烯成为可能。 这个活性空间是目前在内部收缩多参考形式框架内使用的最大的。 DMRG-DSRG方法被应用于几个具有挑战性的系统，包括从萘到十二烷烯的寡聚烯烃的单线态-三线态间隙（$\Delta_{\rm ST}$），玉米黄质的垂直激发能，以及Cr$_2$分子的基态势能曲线（PEC）。 我们对十二烷烯的垂直$\Delta_{\rm ST}$的最佳估计值为0.22 eV，与线性化绝热连接方法（0.24 eV）的结果非常一致。 对于玉米黄质，所有DSRG方案都表明激发态的顺序为$\rm 2\, ^1 A_g^- < 1\, ^1 B_u^+ < 1\, ^1 B_u^-$。 Cr$_2$PEC 的平衡区域和肩部区域均由包含一和二体算符的线性化DSRG合理地再现。 显示英文摘要

摘要： We present a new implementation of the driven similarity renormalization group (DSRG) based on a density matrix renormalization group (DMRG) reference. The explicit build of high-order reduced density matrices is avoided by forming matrix-product-state compressed intermediates. This algorithm facilitates the application of DSRG second- and third-order perturbation theories to dodecacene with an active space of 50 electrons in 50 orbitals. This active space appears the largest employed to date within the framework of internally contracted multireference formalism. The DMRG-DSRG approach is applied to several challenging systems, including the singlet-triplet gaps ($\Delta_{\rm ST}$) of oligoacenes ranging from naphthalene to dodecacene, the vertical excitation energies of zeaxanthin, and the ground-state potential energy curve (PEC) of Cr$_2$ molecule. Our best estimate for the vertical $\Delta_{\rm ST}$ of dodecacene is 0.22 eV, showing an excellent agreement with that of the linearized adiabatic connection method (0.24 eV). For zeaxanthin, all DSRG schemes suggest the order of $\rm 2\, ^1 A_g^- < 1\, ^1 B_u^+ < 1\, ^1 B_u^-$ for excited states. Both the equilibrium and the shoulder regions of the Cr$_2$ PEC are reasonably reproduced by the linearized DSRG with one- and two-body operators.