IBM Research-Zurich, Rüschlikon, Switzerland.
J Chem Phys. 2010 Feb 14;132(6):064104. doi: 10.1063/1.3314220.
The Ragot-Cortona model of local correlation energy [S. Ragot and P. Cortona, J. Chem. Phys. 121, 7671 (2004)] revisits the initial approach of Colle and Salvetti [Theor. Chim. Acta 37, 329 (1975)] in order to reinstate the kinetic contribution T(c) to the total correlation energy E(c). In this work, the one-electron reduced density matrix underlying the amended model is fully derived in closed form. By construction, the said density matrix is parameter-free but not N-representable, owing to approximations used in the Ragot-Cortona approach. However, the resulting density matrix is shown to have formally correct short- and long-range expansions. Furthermore, its momentum-space counterpart qualitatively agrees with known parametrized momentum distributions except at small momenta, where the disagreement reflects the nonrepresentability of the model and restricts to a small fraction of the slowest electrons only.
拉戈特-科尔托纳局部相关能量模型 [S. 拉戈特和 P. 科尔托纳，《化学物理杂志》121, 7671 (2004)] 重新审视了科勒和萨尔维蒂的初始方法 [理论化学学报 37, 329 (1975)]，以便重新引入总相关能量 E(c)中的动力学贡献 T(c)。在这项工作中，修正模型所基于的单电子约化密度矩阵以封闭形式完全推导出来。通过构造，所述密度矩阵是无参数的，但不是 N 可表示的，这是由于拉戈特-科尔托纳方法中使用的近似。然而，所得到的密度矩阵具有形式上正确的短程和长程展开。此外，它的动量空间对应物在定性上与已知的参数化动量分布一致，除了在小动量处，这种不一致反映了模型的不可表示性，并仅限制在一小部分最慢的电子上。
