Hapka Michał, Pastorczak Ewa, Pernal Katarzyna
Faculty of Chemistry, University of Warsaw, Warsaw 00-927, Poland.
Institute of Physics, Lodz University of Technology, Lodz 93-005, Poland.
J Phys Chem A. 2024 Aug 22;128(33):7013-7022. doi: 10.1021/acs.jpca.4c03299. Epub 2024 Aug 8.
We propose a short-range correlation energy correction tailored for active space wave function models. The correction relies on a short-range multideterminant correlation functional computed with a local range-separation parameter that self-adapts to the underlying wave function. This approach is analogous to that of Giner et al. [ , 149, 194301] which addresses the basis set incompleteness error, with the vital distinction that in our protocol the range-separation parameter remains finite in the complete basis set limit, ensuring nonzero short-range correlation. The proposed correlation functional compensates for the missing short-range correlation via two mechanisms: (i) an automatically adapting short-range parameter, which gauges the missing correlation in the electron vicinity, and (ii) the functional's explicit dependence on the on-top pair density, which reduces short-range correlation in regions where electron correlation is mainly static. We integrate our method into the multireference adiabatic connection theory for CASSCF wave functions. The performance of the introduced CAS-AC0-(c,md) model is verified by calculating potential energy curves for alkaline-earth metal dimers (Be, Mg, Ca) and for the chromium dimer, in all cases obtaining promising results.
我们提出了一种针对活性空间波函数模型量身定制的短程相关能校正方法。该校正依赖于一种短程多行列式相关泛函，它通过一个能自适用于基础波函数的局域范围分离参数来计算。这种方法类似于吉纳等人[文献编号，149, 194301]处理基组不完备误差的方法，关键区别在于在我们的方案中，范围分离参数在完备基组极限下仍保持有限，确保了非零的短程相关性。所提出的相关泛函通过两种机制补偿缺失的短程相关性：（i）一个自动适配的短程参数，它测量电子附近缺失的相关性；（ii）该泛函对顶对密度的显式依赖，这减少了电子相关性主要为静态的区域中的短程相关性。我们将我们的方法集成到用于CASSCF波函数的多参考绝热连接理论中。通过计算碱土金属二聚体（Be、Mg、Ca）以及铬二聚体的势能曲线，验证了所引入的CAS - AC0 - (c,md)模型的性能，在所有情况下都获得了有前景的结果。
