This PR modifies the functions in AnisotropicMineral for non-orthotropic materials. Specifically, in non-orthotropic materials, changes in the eigenvectors of deformation mean that the second order compressibility tensor $\boldsymbol{\beta}_T \neq \partial \ln(\boldsymbol{F}) / \partial P|T$, and instead $\boldsymbol{\beta}_T = 0.5( \boldsymbol{L}_P + \boldsymbol{L}^T_P)$, where $\boldsymbol{L}_P = (\partial \boldsymbol{F} / \partial P|T) \boldsymbol{F}^{-1}$.
This has a negligible effect on even non-orthotropic equations of state, but for the avoidance of confusion the correct expressions are implemented here.
This PR modifies the functions in
AnisotropicMineralfor non-orthotropic materials. Specifically, in non-orthotropic materials, changes in the eigenvectors of deformation mean that the second order compressibility tensor $\boldsymbol{\beta}_T \neq \partial \ln(\boldsymbol{F}) / \partial P|T$, and instead $\boldsymbol{\beta}_T = 0.5( \boldsymbol{L}_P + \boldsymbol{L}^T_P)$, where $\boldsymbol{L}_P = (\partial \boldsymbol{F} / \partial P|T) \boldsymbol{F}^{-1}$.This has a negligible effect on even non-orthotropic equations of state, but for the avoidance of confusion the correct expressions are implemented here.