Production of very long aligned carbon nanotubes

Effects of the Jahn-Teller (JT) distortion and the strong electron-electron correlation on the electronic structure of perovskite oxides LaMnO3 are studied by using the linear muffin-tin orbital method. Results show that the Jahn-Teller distortion has evident influence on the electronic structure and its influence varies with different magnetic configurations. On the other hand, the effect of strong electron-electron correlation depends on crystal structures. For distorted LaMnO3 structure, the strong correlation affects the density of states and the band structure lightly, while for undistorted structure, its effect is much stronger. Our calculations indicate that the effect of Jahn-Teller distortion is more pronounced than that of strong electron-electron correlation in LaMnO3 but the latter is important for calculation of total energy. To get the correct ground state as experiments reported for LaMnO3, it is necessary to take the Jahn-Teller distortion, the electron-electron correlation, and antiferromagnetic ordering into consideration simultaneously.