All‐electron fixed‐node diffusion quantum Monte Carlo energies of the two lowest‐lying states of C, N, O, F, and Ne atoms are reported. The Slater‐Jastrow form is used as the trial wave function. We will use single‐ and multideterminant wave functions as the Slater part. The single‐determinant wave function has been computed by the Hartree‐Fock method and the multideterminant wave functions have been computed by the complete active space self‐consistent field, configuration interaction with single and double excitation, configuration interaction with single, double, triple, and quadruple excitation and second‐order configuration interaction. For the ground‐ and first excited states, the multideterminant wave functions have computed more than 99% of the correlation energy. Significant improvements have been achieved using the backflow transformations and up to 99.8% of the correlation energy has been recovered. A very good agreement with the experimental data has been obtained for the excitation energies.

中文翻译：

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使用Slater-Jastrow-回流波函数对C，N，O，F和Ne原子的基态和第一激发态进行量子蒙特卡洛研究

报道了C，N，O，F和Ne原子的两个最低态的全电子固定节点扩散量子蒙特卡洛能量。Slater-Jastrow形式用作试波函数。我们将使用单行和多行波函数作为Slater部分。单行列式波函数是通过Hartree-Fock方法计算的，多行列式波函数是通过完整的活动空间自洽场，具有单激发和双激发的组态相互作用，具有单激发，双激发，三激发，以及四重激发和二阶配置相互作用。对于基态和第一激发态，多行波函数已计算出超过99％的相关能。使用逆流转换已实现了重大改进，并且已回收了高达99.8％的相关能量。激发能与实验数据非常吻合。