QuantumATK Forum

QuantumATK => Scripts, Tutorials and Applications => Topic started by: rs1 on December 3, 2015, 03:49

Title: effective mass direction
Post by: rs1 on December 3, 2015, 03:49

How are the projected effective masses along a particular direction related with the effective mass tensor?

I noted that the "direction_fracational" is a three-dimensional vector, e.g. [1, 0, 1] .  The output vector is also a three-dimensional vector, e.g., [X,0,0], where "X" is the value of the effective mass along a particular direction as specified in the "direction_fractional".

My question is what is the mathematical expression that connects the "direction_fractional" vector, the effective mass tensor and the output vector?

Thanks,
-rs1

Title: Re: effective mass direction
Post by: Troels Markussen on December 3, 2015, 14:56

Hi,

In principle one should be able to obtain the effective mass in direction [hkl] from the effective mass tensor (lets call it M) as [hkl]*M*[hkl]^T.
I am not really clear about what 'output vector' you are referring to  - can you give a code example.

Note, that we have disabled the effective mass tensor functionality in ATK2015. The reason is that we had trouble in getting correct results around degenerate bands. This is, however not a problem if you specify either the 'direction_cartesian' or 'direction_fractional'.

Troels

Title: Re: effective mass direction
Post by: rs1 on December 3, 2015, 19:04

Hi,

In the provided, mathematical relationship:

[hkl]*M*[hkl]^T.

Is the [hkl] vector in defined in Cartesian or fractional coordinates?

Thanks,

Title: Re: effective mass direction
Post by: Troels Markussen on December 7, 2015, 09:44

Hi,

That would be in Cartesian coordinates.

Troels