期刊
JOURNAL OF CHEMICAL PHYSICS
卷 154, 期 5, 页码 -出版社
AIP Publishing
DOI: 10.1063/5.0035883
关键词
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资金
- National Institute of General Medical Sciences of the National Institutes of Health [R01-GM061870]
- National Science Foundation [CHE-1900338]
- Shaffer-Hunnicutt Fellowship from Duke University
The importance of calculating polarizabilities in DFT, particularly for long chain polymers, and the issue of delocalization error in common DFAs are discussed in this work. The results show that applying the LOSC method can significantly improve the description of polarizability, but further adjustment of parameters is needed to enhance accuracy.
Polarizability reflects the response of the molecular charge distribution to an applied external electric field and thus closely relates to the molecular electron density. For the calculation of polarizability within density functional theory (DFT), it is well known that conventional density functional approximations (DFAs) greatly overestimate the results for polymers with long chains and the pi -conjugated system. This is a manifestation of the delocalization error of the commonly used DFAs-they normally produce too delocalized electron density and underestimate the total energy for systems with fractional charge character, which occurs for long molecules in a longitudinal electric field. Thus, to achieve an accurate description of polarizabilities for polymeric molecular systems from DFT, applying DFAs with minimal delocalization error is very important. In this work, we use the recently developed localized orbital scaling correction (LOSC) to the conventional DFAs, which has been shown to largely eliminate the delocalization error, to calculate and study the polarizabilities of three classic polymers, polyyne, polyacetylene, and hydrogen chain. The results from this work demonstrate that applying LOSC to conventional DFAs with self-consistent field calculations can largely improve the description of polarizability from DFT calculations and the improved quality of electron density in LOSC leads to the improved results of polarizability of the polymers. However, the improvement is not complete and adjustment of the parameters in the LOSC method can further improve the accuracy to reach the level similar to the MP2 method. This work also points to the direction for the further development of LOSC in self-consistent calculations.
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