The electronic structure and magnetic properties of the strongly correlated material La2O3Fe2Se2 are studied by using both the density function theory plus U (DFT+U) method and the DFT plus Gutzwiller (DFT+G) variational method. The ground-state magnetic structure of this material obtained with DFT+U is consistent with recent experiments, but its band gap is significantly overestimated by DFT+U, even with a small Hubbard U value. In contrast, the DFT+G method yields a band gap of 0.1 - 0.2 eV, in excellent agreement with experiment. Detailed analysis shows that the electronic and magnetic properties of of La2O3Fe2Se2 are strongly affected by charge and spin fluctuations which are missing in the DFT+U method.
@article{arxiv.1511.09195,
title = {Strong charge and spin fluctuations in La$_2$O$_3$Fe$_2$Se$_2$},
author = {Guangxi Jin and Yilin Wang and Xi Dai and Xinguo Ren and Lixin He},
journal= {arXiv preprint arXiv:1511.09195},
year = {2016}
}