N.H.March
材料科学技术（英文）
A condition for local moment formation in metals derived by Stoddart and March (Ann. Phys. NY 1972 64, 174) is first used to discuss the ferromagnetism of body-centred-cubic Fe. A less detailed discussion is also added on Ni and Co. This leads into a treatment of the nonlinear response of such 3d ferromagnets to dilute substitutional impurities. Antiferromagnets responding to local changes in the exchange field caused by such impurities are also studied, Mn in Cr being one such system discussed. The paper concludes with a brief summary of clusters of transition metal atoms, with most attention devoted to Cr and to Mn.
关键词:
N.H.March
材料科学技术（英文）
The coordination-dependent force field of Tersoff for covalently bonded Si has been used to calculate the cleavage force as a function of interplanar separation and hence to estimate surface energies. This force field is already fitted to density functional results. The relation to bond-breaking and electron correlation will be emphasized. Finnis-Sinclair-type many-body potentials have then been used to treat some d-electron metals. In particular, results for cleavage force in bcc Fe will be presented, and also some calculations as two perfectly planar Fe surfaces are `rubbed together' at different interplanar separations. Finally, lattice dynamical models for the steady-state propagation of a screw dislocation, and then of a crack, will be used, again within a bond-breaking type of force field. For the screw dislocation propagation, a solitary wave equation is shown to follow in the ‘almost continuum' limit. Energy radiated by phonons as the dislocation moves can thereby be calculated.
关键词:
