Borel, Jean-PierreGhez, Richard2005-03-162005-03-16196810.5075/epfl-thesis-73https://infoscience.epfl.ch/handle/20.500.14299/201216The gibbsian model for surfaces is reformulated in order to account for stress and strain within quasi-ideal crystals and on their surface. Tensor calculus, extensively used, leads to an invariant formalism. The symbols appearing therein are given a physical interpretation. The Second Principle, applied to the crystal-crystalline surface-vapour system, yields necessary equilibrium conditions. Herring's formula for the chemical potential is derived as a special case. The validity of the usual assumptions relating to shape equilibria are investigated.frthesis::doctoral thesis