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The phase field crystal method is used to simulate the healing process of the central gap of 3-dimensional BCC crystal material under compression strain at the atomic level. It is found that during the healing process of the central gap, the gap protrudes at both ends of it, leading to dislocation nucleation and vacancy formation. Then, by means of dislocation nucleation and dislocation emission mechanism at both ends of the gap, the thickness of the gap is reduced by one layer of atoms, and the atomic layer on the gap surface shrinks towards each other. Through the mechanism of dislocation nucleation and dislocation emission, the thickness of gap is reduced layer by layer, and finally the connection and closure of the lattice atoms on up and down surface of the gap is achieved, and the surface healing of the central gap is realized. According to the sharpening and passivation mechanism of the lattice atomic planes at both ends of the gap, the elliptic shape gap is approximated to calculate and analyze the influence of the change of stress intensity factor during the gap healing, and the critical condition of the gap dislocation emission is determined.

Aiming at the strain distribution around the atomic lattice defect with void and crack in crystal materials, a new elastic strain calculation method named as center atom model (CAM) is proposed in this work, and is applied for mapping the strain field of the defect with void in an atomic image lattice in real space under external forcing. As an example, the strain mapping of voids and cracks of an atomic lattice image from phase field crystal (PFC) model is quantitatively characterized by CAM. The results show that CAM can well be used to extract the strain information from various types of the defect surface of atomic lattice images. Wherever the strain distribution around the dislocation of the grain boundary or the strain around the void and crack is, CAM can accurately extract the strain distribution of the distortion area of the atomic lattice. CAM can also be easily extended and applied to the strain mapping of the defects in the heterogeneous interface.

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