Theoretical study of the electronic, structural, and cohesive properties of ruthenium

The electronic, structural, and cohesive properties of ruthenium in the hexagonal-close-packed structure are calculated by using a local-orbital ab initio pseudopotential method. We determine the lattice parameters, Poisson's ratio, the cohesive energy, and the bulk modulus by calculating the total energy of the solid-state system as a function of the lattice parameters c and a. We also predict the value of the c/a ratio up to pressures of 1 Mbar. We find that as a function of pressure the c/a value approaches the ideal value. Overall, the agreement with the observed lattice parameters is quite good. The largest structural error is in the c lattice parameter and is approximately 2%. The cohesive energy is larger than experiment by approximately 15% and is consistent with other local-density calculations for transition metals. The calculated band structure is in accord with photoemission measurements.