Hi aimipa!

Yes there is an option to set an anisotropic grid from NEWK, you can find it at page 346 of the CRYSTAL User's Manual, see also the screenshot I attach below. You have to set IS=0 and then you can choose three different shrinking factors along B1, B2 and B3.

For example:

sets a shrinking factor of 12, 8 and 4 along the three reciprocal lattice vectors.

I have never tested this anisotropic option in a BOLTZTRA calculation, would you mind let me know if it works? 🙂

newk.png