<正> The phenomenon of interfacial fracture, as manifested by atom-istic cleavage, debonding and dislocation emission, provides a challenge for combinedatomistic-continuum analysis. As a precursor for fully coupled atomistic-continuumsimulation of interfacial fracture, we focus here on the atomistic behavior withina nanoscopic core surrounding the crack tip. The inter-atomic potential under Em-bedded Atom Method is recapitulated to form an essential framework of atomisticsimulation. The calculations are performed for a side-cracked disc configuration un-der a remote K field loading. It is revealed that a critical loading rate defines thebrittle-to-ductile transition of homogeneous materials. We further observe that thenear tip mode mixity dictates the nanoscopic profile near an interfacial crack tip. Azigzag interface structure is simulated which plays a significant role in the dislocationemission from an interfacial crack tip, as will be explored in the second part of thisinvestigation.