First Principle Ab-initio Study of TiO$_2$

POSTER

Abstract

We report results from first principle computations of electronic properties of rutile TiO${_2}$ within the local density functional approximation (LDA). Our first principle, non-relativistic and ground state calculations employed a local density functional approximation (LDA) potential and the linear combination of atomic orbitals (LCAO) -- utilizing a self-consistently obtained, optimized basis set. We solved self-consistently both the Kohn-Sham equation and the equation giving the ground state charge density in terms of the wave functions of the occupied states. Our calculated band structure shows that there is significant O$_2p$-Ti$_3d$ hybridization in the valence bands. These bands are well separated from the conduction bands by an indirect band gap of 2.95 eV, from $\Gamma$ to R. Consequently, this work predicts that rutile TiO$_2$ is an indirect band gap material, as all other gaps from our calculations are larger than 2.95 eV. A slightly larger, direct band gap of 3.05 eV is found at the $\Gamma$ point, in excellent agreement with experiment. Our structural optimization led to lattice parameters of 4.65 {\AA} and 2.97 {\AA} for $a_o$ and c$_o$, respectively, with a u parameter of 0.3051, and a bulk modulus of 215 GPa.

*This work was funded in part by the the National Science Foundation (Award Nos. 0754821, EPS-1003897, and NSF (2010-15)-RII-SUBR), the Department of the Navy, Office of Naval Research (ONR, Award No. N00014-04-1-0587), and Ebonyi State, Nigeria

Authors

  • Chinedu Ekuma

    • Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA
    • Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA

  • Mark Jarrell

    • Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA
    • Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA
    • Louisiana State University
    • Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA
    • Louisiana State University (LSU)
    • Department of Physics and Astronomy, Louisiana State University
    • Department of Physics \& Astronomy, Louisiana State University

  • Juana Moreno

    • Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA
    • Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA
    • Louisiana State University
    • Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA
    • Department of Physics and Astronomy, Louisiana State University
    • Department of Physics \& Astronomy, Louisiana State University

  • Diola Bagayoko

    • Southern University and A\&M College, Baton Rouge, LA 70803, USA
    • Department of Physics Southern University and A\&M College, Baton Rouge, LA 70813
    • Department of Physics, Southern University and A\&M College, Baton Rouge, LA 70813