# Parameters for calculating effectiveMass

Parameters here are for effective mass calculations.

## calculation.effectiveMass.massParameters

**keyword**: calculation.effectiveMass.massParameters

**possible values**: n x 5 cell matrix

**default value**: no default value, must be given

**description**: The parameter is an n x 5 cell matrix. Each row, having
5 cells, defines an effective mass which is to be
calculated:

(1) The first cell contains string ‘’hole’’ or ‘’electron’’, indicating that an electronic or a hole effective mass will be calculated.

(2) The second cell contains an integer which is used to indicate the energy band; 1 is for the conduction band, 2 for the second conduction band, and so on; -1 is for the valence band, -2 for the second valence band, and so on.

(3) The third cell contains an integer which is used to indicate the spin component; 1 is for spin up and 2 for spin down. For no spin system or general spin system, it is always set to be 1.

(4) The fourth and fifth cells contain two k-points, defining a line segment on which a maximum / minimum point will be found and the effective mass is calculated at the maximum / minimum point. The two k-points are given by their fractional coordinaters. Please note that for a k-point with coordinates k1, k2, and k3, the corresponding k-vector is k-vector = k1 X b1 + k2 X b2 + k3 X b3, where b1, b2, and b3 are defined through dot(b_i, a_j) = 2pi x delta_{i,j}, and a1, a2, a3 are the central cell vectors used in the self-consistent-field calculation.

**an example**:

```
calculation.effectiveMass.massParameters = ...
{'hole', -1, 1, [0 0 0], [1/2 1/2 1/2], ; ...
'electron', 1, 1, [0 0 0], [0 1/2 1/2]}
```