results

[jinghuirong]

hello,I need your help,I use emc.py code with vasp and got result, but the result are different from others, I paste my result in bellow, the effective mass along three directions are 0.031 0.031 0.088, other paper is 0.063,0.063, 0.410, and I found the three directions are perpendicular，0.088 corresponding 111 direction, in other's paper, this direction effective mass is 0.410，the second issue is, in other Kpoint(not high-symmetry kpoints), the eigenvectors are random, I want to know if there is a code I can get the effective mass in a fixed direction,thankyou
Contents of the input_file file:

0.500 0.500 0.500
0.01
20
V
0.000000000 3.285539473 3.285539473
3.285539473 0.000000000 3.285539473
3.285539473 3.285539473 0.000000000

==========

Successfully opened EIGENVAL, preparing to parse it...

-> fd_effmass_st3: Effective mass tensor:

-25.35629843 6.98108529 6.98108529
6.98108529 -25.35629843 6.98108529
6.98108529 6.98108529 -25.35629843

Principle effective masses and directions:

Effective mass (0): -0.031
Original eigenvectors: -0.70711 0.70711 0.00000
Normal fractional coordinates: 1.00000 -1.00000 0.00000

Effective mass (1): -0.031
Original eigenvectors: -0.40825 -0.40825 0.81650
Normal fractional coordinates: -0.50000 -0.50000 1.00000

Effective mass (2): -0.088
Original eigenvectors: 0.57735 0.57735 0.57735
Normal fractional coordinates: 1.00000 1.00000 1.00000

[afonari]

You can't get the effective mass in a fixed direction using this method. Since directions are the eigenvectors of the matrix. You can use parabola method to compute eff mass along a certain direction.

Have you tried changing the step size? sometimes it changes the direction.