Effect of surface interactions on spin contamination errors of homogeneous spin dimers, chains, and films: model calculations of Au/MgO and Au/BaO systems

Abstract

It is well known that unrestricted density functional theory (UDFT) calculations include spin contamination errors. While errors in UDFT/plane-wave calculations have not been clarified thus far, some effects of these errors are investigated. Recently, our group estimated spin contamination errors in UDFT/plane-wave calculation results by developing and applying the approximate spin projection (AP) scheme [Chem. Phys. Lett., 701: 103 (2018), Mol. Phys., 117: 2251 (2019), Molecules, 24: 505 (2019), Appl. Phys. Express, 12: 115506 (2019)]. In this study, a systematic theoretical investigation of the surface effects on the spin contamination error was performed. For this purpose, we selected model systems such as Au dimers, chains, and film adsorptions onto MgO and BaO (001) surfaces. The calculation results showed the dependence on the dimensions of the supported materials and lattice constants of the supports. In general, the effects of spin contamination errors are decreased by interaction with the surface. The effects of the errors increased by increasing dimension; i.e. the increasing order of spin contamination errors is film > chain > dimer. In addition, the spin-polarised states are stabilised because of the interaction with the surfaces, and spin contamination errors occur in some cases where the Au–Au distances are small.

GRAPHICAL ABSTRACT

KEYWORDS:

• Spin contamination error
• surface interaction
• AP-DFT/plane-wave

Acknowledgments

The authors are grateful to Prof. Dr. Kizashi Yamaguchi, Dr. Takashi Kawakami, and Dr. Yasutaka Kitagawa for their theoretical supports. This work was supported by JSPS KAKENHI (grant number 20K15177). This work was also conducted under the management of the ‘Elements Strategy Initiative for Catalysts and Batteries (ESICB),’ supported by the Ministry of Education, Culture, Sports, Science, and Technology, Japan. The authors would like to thank Editage (www.editage.jp) for English language editing. Computations described in this work were carried out using the computer facilities at the Research Institute for Information Technology, Kyushu University.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by JSPS KAKENHI (grant number 20K15177). This work was also conducted under the management of the ‘Elements Strategy Initiative for Catalysts and Batteries (ESICB),’ supported by the Ministry of Education, Culture, Sports, Science, and Technology, Japan; Japan Society for the Promotion of Science.