Role of Fermi surface and crystal structure in theory of magnetic metals

Journal ArticleWe have investigated the magnetic ground state of metals using an idealized theory of magnetism based on the Ruderman-Kittel-Yosida indirect exchange interaction. The preliminary, but suggestive, results reported here are for simple cubic structures and spherical Fermi surface. We find that as the number of electrons is increased, ferromagnetism is replaced by two different antiferromagnetic structures before the Neel state is finally obtained

CALCULATIONS ON F−F^{-}, Ne, AND NA+NA^{+} GROUND STATES

Author Institution: IBM Research Dept., Watson LaboratoryWavefunctions are calculated for the ground states of these ions using the method of configuration interaction. The first configuration was made up of orbitals which were analytic fits to the Hartree Fock functions for these ions. Ten configurations were introduced which provided correlation among the outer shell electrons. Two configurations were included to allow modification of the 2s and 2p electrons. The improvement in the energy was about half the total correlation energy. The method of configuration interaction was then used to locate sets of 5 and 8 excited states of $^{1}P$ symmetry. These were used to make calculations of the polarizability and London Force Coefficients, using both H.F. and C.I. functions for the ground state

INTERACTION OF ELECTRONS IN POLAR SOLVENTS OR LATTICES

Author Institution: Polytechnic Institute of BrooklynA model, presented here for the bipolaron, puts the two electrons into a configuration which is essentially that of a hydrogen molecule without the nuclei. The model is applicable for the case of a solvent, or lattice, and assumes that the Born Oppenheimer approximation applies. Calculations will be presented for different average separations. It will be shown that for large rations of static to dynamic polarizability the bipolaron is stable, in contrast to previous work, which did not include electron correlation effects."

Demonstrating the Scalability of a Molecular Dynamics Application on a Petaflop Computer

The IBM Blue Gene project has endeavored to develop a cellular architecture computer with millions of concurrent threads of execution. One of the major challenges of this project is demonstrating that applications can successfully exploit this massive amount of parallelism. Starting from the sequential version of a well known molecular dynamics code, we developed a new application that exploits the multiple levels of parallelism in the Blue Gene cellular architecture. We perform both analytical and simulation studies of the behavior of this application when executed on a very large number of threads. As a result, we demonstrate that this class of applications can execute efficiently on a large cellular machine