How to obtain elastic constants using first-principles calculation - 2. Strain and Stress
2. Strain and Stress In order to describe the changes of displacements, strain is necessary to be defined. The configuration in the infinitesimal neighborhood around points is represented as follows: For the more for this, the Lagrangian strain tensor can be defined. In case of stress, the Cauchy stress tensor is used to describe the state of stress in the solid. , which is the force acting outwards on a surface region . Thanks JF