抄録
It has been argued theoretically that a new state, namely, no halogen displacements around Pd ions and, consequently, their trivalent states with finite magnitudes of spin, will be realized by at least 50%-inclusion of Ni ions in Pd-Ni mixed-metal MX-chains. This state is peculiar to such mixed-metal systems, because it is never found as a ground state for homo-metal chains of Pd. Moreover, from the theoretical viewpoint, strong electron-lattice interaction and strong electron-electron Coulombic repulsion are mixed up to give a very interesting example for the study of both. Here we go beyond the previous theoretical work that was based on a Hartree-Fock (HF) calculation and investigate the same system by a quantum Monte-Carlo method applied to a Peierls-Hubbard model. The obtained result is qualitatively the same as the previous one and therefore reinforces the above interpretation with a preliminary result for magnetic susceptibility. Moreover, we show statistically averaged lattice states for rather continuous composition changes, within the framework of HF calculations. The obtained result explains well the Raman data.
