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Comparative study of structural and electronic properties of TiO2 at GGA and GGA+U level

TARIQ MAHMOOD1,2, CHUANBAO CAO1, R. AHMED3,* , M. A. SAEED3, MAQSOOD AHMED2

Affiliation

  1. School of Materials Science and Engineering, Beijing Institute of Technology, Beijing-100081, P.R. China
  2. Centre for High Energy Physics, University of the Punjab, Lahore-54590, Pakistan
  3. Physics Department, Faculty of Science, Universti Teknologi Malaysia, Skudai-81310, Johor, Malaysia

Abstract

Besides the structural properties, electronic bandstructure investigations of two technologically important phases (anatase and rutile) of titanium dioxide (TiO2) are studied in this research using DFT based first-principles plane-wave ultrsoft pseudo-potential (PW-PP) scheme of calculations as implemented in CASTEP computational code. In these Computations, for exchange-correlation functional, Perdew-Burke-Ernzerhof (PBE) parameterized generalized gradient approximation (GGA) and GGA+U are implemented, where ‘U’ is Hubbard correction parameter for screening self interaction. Optimum value of U applied in this study for rutile is 7.5eV, and for anatase is 9.0eV. Our calculated values of bandgap energy with PBE-GGA for anatase and rutile structure are 2.140eV and 1.973eV respectively which are sufficiently underestimated in comparison with experimental measurements whereas computed bandgap energy values within the implementation of GGA+U are found to be 3.350eV and 2.557eV respectively. These results are in nice agreement to experiment. Furthermore, to obtain the equilibrium volume, bulk modulus and pressure derivative, equation of state calculations were taken into account. Our calculated results for structural properties for anatase (V0=141.7 3 0Α , B0=417.4GPa and ' 0B =3.97, and rutile (V0=65.68 3 0Α , B0=153.24GPa and ' 0B =3.7) phases agree well with experimental as well as previously reported first principles studies..

Keywords

DFT+U, CASTEP, Bandgap, TiO2, Wide gap semiconductors.

Submitted at: March 18, 2013
Accepted at: Jan. 22, 2014

Citation

TARIQ MAHMOOD, CHUANBAO CAO, R. AHMED, M. A. SAEED, MAQSOOD AHMED, Comparative study of structural and electronic properties of TiO2 at GGA and GGA+U level, Journal of Optoelectronics and Advanced Materials Vol. 16, Iss. 1-2, pp. 117-122 (2014)