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arXiv · 0905.1767

Accurate projected augmented wave datasets for BaFe$_2$As$_2$

Chao Cao·Yu-ning Wu·Rashid Hamdan·Yun-Peng Wang·Hai-Ping Cheng
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Abstract

By carefully choosing parameters and including more semi-core orbitals as valence electrons, we have constructed a high quality projected augmented wave (PAW) dataset that yields results comparable to existing full-potential linearized augmented plane-wave calculations. The dataset was then applied to BaFe$_2$As$_2$ to study the effects of different levels of structure optimization, as well as different choices of exchange-correlation functionals. It is found that the LDA exchange-correlation functional fails to find the correct SDW-AFM ground state under full optimization, while PBE exchange-correlation functional obtains the correct state but significantly overestimates the magnetism. The electronic structure of the SDW-AFM state is not very sensitive to structure optimizations with the PBE exchange-correlation functional because the position of the As atoms are preserved under optimizations. We further investigated the Ba atom diffusion process on the BaFe$_2$As$_2$ surface using the nudged elastic bands (NEB) method. The Ba atom was found to be stable above the center of the squares formed by the surface As atoms, and a diffusion barrier of 1.2 eV was found. Our simulated STM image suggests an ordered surface Ba atom structure, in agreement with Ref.

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Chao Cao, Yu-ning Wu, Rashid Hamdan, Yun-Peng Wang, Hai-Ping Cheng. 2010-12-27. Accurate projected augmented wave datasets for BaFe$_2$As$_2$. https://doi.org/10.1088/1367-2630%2F12%2F12%2F123029

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