Publication:
First Principles Enhanced Electronic Band Structure of SrTiO₃ using DFT+U Method
First Principles Enhanced Electronic Band Structure of SrTiO₃ using DFT+U Method
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Date
2019-01
Authors
Akeem Adekunle Adewale
Abdullah Chik
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Universiti Malaysia Perlis (UniMAP)
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Abstract
Density functional theory (DFT) technique was used to study the influence of Hubbard U on the calculated electronic properties of perovskite SrTiO₃. We used the Quantum Espresso (QE) software package with exchange-correction energy function within local density approximation for DFT and DFT+U calculations. The band structure, total and partial density of states (DOS and PDOS) were calculated. Three set of methods were adopted in the calculations: DFT without U, DFT+U with calculated U through linear response theory, and DFT+U with manually increment of U value. The calculated Hubbard U using linear response theory is 3.27 while selected U for manual increment method were chosen from 4.27 to 10.27 with an interval of 1. For DFT and DFT+U with calculated U, the calculated band gaps were 1.80 and 2.19 eV respectively. During increasing of U the calculated band gap were increasing from 2.43 eV (@U=4.27) and reaches peak of 3.06 eV (@U=8.27) which later reduce to 2.19 eV (@U=10.27). Therefore, DFT+U method with incremental Hubbard U resulted in better band gap value of 3.06 eV that is closer to the experimental result of 3.25 eV.
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Keywords
QE,
Energy band gap,
Density of state,
Hubbard-U parameter,
DFT,
DFT+U,
SrTiO₃