Can anybody tell me how to calculate lattice misfit strain. There are n-numbers of literature and authors wrote about it and confused their own way. Let me say I have a film "a" which grows on substrate "b" and it is hetero epitaxial. I know the orientation relationship which follows like (010)a//(111)b and a//b. In this situation what should be the lattice misfit strain beween film and the substrate? Do I have to calculate the misfit in terms of d-spacing in this plane? or do I have to calculate the lattice vector in that direction.The structure is monoclinic(film-a) on cubic (substrate-b). Looking for some sensible answer.