Abstract
In this paper we explore a possible method to couple atomistic modeling of initiation of fracture in iron with displacement constraints taken from continuum considerations. Molecular dynamics is used to examine the effect of a penny-shaped crack, and the quasicontinuum method is used as a platform for performing multiscale analysis. The modified boundary layer approach enables us to examine the influence of constraint (geometry, crack size and mode of loading) on the fracture mechanisms by changing the T-stress (the constant term in the stress series expansion). The results are discussed in relation to how constraint influences upon the crack initiation toughness.