Excited-State DMRG Made Simple with FEAST

We introduce DMRG­[FEAST], a new method for optimizing excited-state many-body wave functions with the density matrix renormalization group (DMRG) algorithm. Our approach applies the FEAST algorithm, originally designed for large-scale diagonalization problems, to matrix product state wave functions. We show that DMRG­[FEAST] enables the stable optimization of both low- and high-energy eigenstates, therefore overcoming the limitations of state-of-the-art excited-state DMRG algorithms. We demonstrate the reliability of DMRG­[FEAST] by calculating anharmonic vibrational excitation energies of molecules with up to 30 fully coupled degrees of freedom.

我们提出了DMRG[FEAST]——一种基于密度矩阵重整化群（density matrix renormalization group, DMRG）算法优化激发态多体波函数的新方法。本方法将原本针对大规模对角化问题设计的FEAST算法，应用于矩阵乘积态波函数。我们证明，DMRG[FEAST]可实现低能与高能本征态的稳定优化，从而突破当前主流激发态DMRG算法的局限性。我们通过计算多达30个全耦合自由度的分子非简谐振动激发能，验证了DMRG[FEAST]的可靠性。