The geometric structures and electronic structures of tungsten bronzes Na_xWO₃ and Na_x- La_yWO₃ (x＞0.36, y＜0.015) have been explored by den-sity functional theory (DFT). The geometry was optimized using ADF (Amsterdam density functional) pro-gram package with TZ2P basis set. The energy bands and density of states were calculated using the VASP (Vienna ab-initio simulation package) program. The calculated structures are close to the experi-mental values. After the substitution of La^3＋ for Na^＋, the space symmetry is not changed but the lattice parameters and volumes of Na_xLa_yWO₃ increase. The energy bands are con-densed and the appearance probabilities of the electrons are enhanced near the Fermi-surface. Therefore, the introduction of La^3＋ is important to improve the conductivity of the sodium tungsten bronze.

Key words: tungsten bronze, Na_xLa_yWO₃, electron conductivity, geometry optimization, band structure, density of states