Effective Mass

Current status: READY

Near a parabolic extremum,

$$E(\mathbf k) \approx E_0 + \frac{\hbar^2}{2} (\mathbf k-\mathbf k_0)^T (m^*)^{-1} (\mathbf k-\mathbf k_0),$$

so

$$(m^{*-1})_{ij} = \frac{1}{\hbar^2} \frac{\partial^2E}{\partial k_i\partial k_j}.$$

The user chooses electron/hole and CBM/VBM behavior. Analyze shows the source data and fitted parabola.

Insufficient sampling returns an explicit diagnostic rather than a zero or NaN mass.