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We have evaluated the successes and failures of the Hubbard-corrected density functional theory (DFT+U) approach to study Mg doping of LiCoO$_2$. We computed the effect of the U parameter on the energetic, geometric and electronic properties of two possible doping mechanisms: (1) substitution of Mg onto a Co (or Li) site with an associated impurity state and, (2) formation of impurity-state-free complexes of substitutional Mg and point defects in LiCoO$_2$. We find that formation of impurity states results in changes on the valency of Co in LiCoO$_2$. Variation of the Co U shifts the energy of the impurity state, resulting in energetic, geometric and electronic properties that depend significantly on the specific value of U. In contrast, the properties of the impurity-state-free complexes are insensitive to U. These results identify reasons for the strong dependence on the doping properties on the chosen value of U and for the overall difficulty of achieving agreement with the experimentally known energetic and electronic properties of doped transition metal oxides such as LiCoO$_2$.
The response of a one-dimensional fermion system is investigated using Density Functional Theory (DFT) within the Local Density Approximation (LDA), and compared with exact results. It is shown that DFT-LDA reproduces surprisingly well some of the ch
We present in full detail a newly developed formalism enabling density functional perturbation theory (DFPT) calculations from a DFT+$U$ ground state. The implementation includes ultrasoft pseudopotentials and is valid for both insulating and metalli
We use dispersion-corrected density-functional theory to determine the relative energies of competing polytypes of bulk layered hexagonal post-transition-metal chalcogenides, to search for the most stable structures of these potentially technological
Using the first-principles density-functional theory plan-wave pseudopotential method, we investigate the structure and magnetism in 25% Mn substitutive and interstitial doped monoclinic, tetragonal and cubic ZrO2 systematically. Our studies show tha
Recent experiments demonstrate the synthesis of 2D black arsenic exhibits excellent electronic and transport properties for nanoscale device applications. Herein, we study by first principle calculations density functional theory together with non eq