Recently I am learning VASP. I am trying to see different properties of two-level system (TLS). For example, checking amorphous silicon as a test case (along with it's vacancy structures as well). From these structures, I have the following information for different structures so far:
Stress tensors: ii, ij, ik, ji, jj, jk, ki, kj, kk Elastic tensors: C_11, C_22, C_33, C_12, C_13, C_23, C_44, C_55, C_66, C_16, C_26, C_36, C_46, C_56, C_14, C_15, C_25, C_45 Volume Total Energy
Now, it would be great to get your detailed suggestion about how can I calculate an elastic dipole and strain field from a TLS?
More specifically, this would be the difference in the strain field between the two different atomic configurations? Do we need just the elastic dipole difference of the TLS and the elastic constants of the material? Or do we need something else?
Any detailed theoretical idea (as well as any software suggestions including their tutorials - if needed) and/or coding idea would be greatly appreciated - as I am new in learning this. Thanks in advance for your cooperation.
This paper might be helpful to get answers for the above (though I have not been able to figure it out from it): Paper