A phenomenological theory of this effect which explained it in terms of the flattening of a free energy profile was formulated by Landau, Ginsburg, and Devonshire. The tensor coefficients used in the description of this phenomenon can be written in terms of the Born effective charge tensors. The polarization in this phenomenon is computed via this effect's namesake tensor contracted with the strain tensor, and the field can then be obtained from the Poisson equation, which is combined with the elasticity and continuity equations to describe this phenomenon. This effect, which is applicable in situations where fine-grained control is required, such as the axis drives of a scanning tunneling microscope, occurs in crystals without inversion centers, such as quartz. For 10 points, identify this effect in which a mechanical deformation results in a restoring electric 
A phenomenological theory of this effect which explained it in terms of the flattening of a free energy profile was formulated by Landau, Ginsburg, and Devonshire. The tensor coefficients used in the description of this phenomenon can be written in terms of the Born effective charge tensors. The polarization in this phenomenon is computed via this effect's namesake tensor contracted with the strain tensor, and the field can then be obtained from the Poisson equation, which is combined with the elasticity and continuity equations to describe this phenomenon. This effect, which is applicable in situations where fine-grained control is required, such as the axis drives of a scanning tunneling microscope, occurs in crystals without inversion centers, such as quartz. For 10 points, identify this effect in which a mechanical deformation results in a restoring electric field, and vice versa.
A phenomenological theory of this effect which explained it in terms of the flattening of a free energy profile was formulated by Landau, Ginsburg, and Devonshire.
piezoelectricity [or electrostriction] 