Electronic Band Structure and Photoemission States of $La_{2//3}Pb_{1//3}MnO_3$

We present the theoretical study of electronic and magnetic properties in a manganese perovskite $La_{2//3}Pb_{1//3}MnO_3$. The calculations were carried out in frame of the first-principles density functional theory with the general gradient approximation using the WIEN 2K package. The P3c1 crystal structure was taken from the detailed X-ray diffraction data for the perovskite. The exact exchange energy was utilized for Mn d electrons. Density of states was determined by the modified tetrahedron method. As a result we get a valence band for the spin up and down density of states with the gap for the latter of 1.85 eV. We noticed that conduction band is mainly dominated by d spin up manganese electrons and $Mn (d_{xz}, d_{yz})$ states have twice larger contribution than $(d_{x^2 - y^2}, d_{xy})$. We attribute this to $Mn-O_6$ octahedral tilting. From the same reason $d_{3z^2 - r^2}$ state has no contribution to the density of states at the Fermi energy $(E_{F})$. Comparison of total density of states with the ultraviolet photoemission spectroscopy measurements shows similar features especially as far as the lead spectral intensity from the 6s electrons at about - 10 eV is concerned. The calculated total magnetic moment per formula unit is 3.66 $μ_{B}$, the measured one 3.48 $μ_{B}$/f.u.