论文标题
来自片段和周期方法的分子固体的结合能
Binding energies of molecular solids from fragment and periodic approaches
论文作者
论文摘要
我们使用Hartree-Fock（HF）和二阶Møller-Plesset扰动理论（MP2）计算四个分子固体的结合能。我们在多体扩展（MBE）中获得能量，并使用周期性边界条件（PBC）比较两种方法。我们研究的系统是甲烷，二氧化碳，氨和甲醇。我们使用紧密的收敛设置以高精度获得结合能，我们估计不确定性仅为十分之数。我们讨论了影响结果质量的几个问题，并且需要考虑到MBE和PBC内的高精度。例如，PBC中的HF和MP2能量受益于使用真实空间库仑截止技术，通过修改求和顺序，可以改善MBE内能量的收敛。最后，数值噪声使对某些MBE贡献的评估变得难以评估，并且通过使用较小的基集对较不关键的术语使用较小的基集来降低效果。
We calculate binding energies of four molecular solids using the Hartree-Fock (HF) and second-order Møller-Plesset perturbation theory (MP2). We obtain the energies within many-body expansion (MBE) as well as using periodic boundary conditions (PBC) to compare both approaches. The systems we study are methane, carbon dioxide, ammonia, and methanol. We use tight convergence settings to obtain the binding energies with a high precision, we estimate the uncertainties to be only few tenths of percent. We discuss several issues that affect the quality of the results and which need to be considered to reach high precision for both MBE and within PBC. For example, HF as well as MP2 energies within PBC benefited from the use of real-space Coulomb cut-off technique, the convergence of energies within MBE was improved by modifying the order of summation. Finally, numerical noise made the evaluation of some of the MBE contributions difficult and the effect was reduced by using smaller basis sets for the less critical terms.
