School of Physics and Materials Science, Anhui University, Heifei 230601, China.
J Chem Phys. 2013 May 7;138(17):174116. doi: 10.1063/1.4802961.
An efficient, yet very accurate trial wave function, constructed from projecting the well-known Davydov D1 Ansatz onto momentum eigenstates, is employed to study the ground state properties of the generalized Holstein Hamiltonian with simultaneous diagonal and off-diagonal coupling. Ground-state energies have been obtained with a precision matching that of the computationally much more demanding density-matrix renormalization group method. The delocalized D1 Ansatz lowers the ground-state energies at the Brillouin zone boundary significantly compared with the Toyozawa and Global-Local Ansätze in the weak coupling regime, while considerable improvement is demonstrated to have been achieved over the entire Brillouin zone in the strong coupling regime. Unique solutions are obtained with the delocalized D1 for different initial conditions when the transfer integral is 20 times the phonon frequency at the zone center, implying the absence of any self-trapping discontinuity. The scaled correlation variance is found to fit satisfactorily well with the predictions of the perturbation theories.
采用一种高效且非常准确的试探波函数，通过将著名的 Davydov D1 Ansatz 投影到动量本征态上构建，用于研究具有同时对角和非对角耦合的广义 Holstein 哈密顿量的基态性质。通过与计算要求高得多的密度矩阵重整化群方法相匹配的精度，得到了基态能量。在弱耦合区域中，与 Toyozawa 和 Global-Local Ansätze 相比，离域 D1 Ansatz 显著降低了 Brillouin 区边界的基态能量，而在强耦合区域中，在整个 Brillouin 区都取得了相当大的改进。当转移积分是区中心声子频率的 20 倍时，对于不同的初始条件，离域 D1 获得了独特的解，这意味着不存在任何自陷不连续性。发现标度相关方差与微扰理论的预测非常吻合。
