Yoji Shibutani

Nonlocal properties of inhomogeneous structures by linking approach of generalized continuum to atomistic model

Nonlocal elastic constants associated with strain gradient terms in the Cosserat theory are linked to atomic-level properties, in particular to coefficients that arise in lattice dynamics equations when atomic displacements are expressed in terms of a continuous displacement field. Therefore, the nonlocal elastic constants, including the ordinary fourth-order ones, are expressed in terms of only both the atomic positions in a relaxed configuration and the force constants which are the second derivative of the employed interatomic potential with respect to an atom position. Molecular statics and molecular dynamics simulations of stable (or meta-stable) surface and grain boundary structures are performed using a Finnis-Sinclair-type many-body potential. Then, the nonlocal properties are discussed, being compared with homogeneous bulk properties to identify the characteristic length over which nonlocal effects associated with the inhomogeneous structures are significant.