Compare the total energies of supercells w/ different sizes
Posted: Tue Feb 12, 2013 6:28 pm
Hi all,
I am trying to relax some superlattices, and find the ground state(or low-energy) structures. To take some distortions into account I would need larger supercell than others.
I know that we cannot directly compare the total energies of two structures with different sizes due to the problem of k-points. However, is there any good ways to do this?
Let's say I have two supercells, one is 2x2x4 and the other is sqrt(2)xsqrt(2)x4. Surely I can contain the same distortion patterns of sqrt(2)xsqrt(2)x4 cell in the 2x2x4 cell, but if there is a way to reduce the cost of time, that would be excellent. I am not sure how can I make their k meshes equivalent in this case...
Thanks,
Yuanjun
I am trying to relax some superlattices, and find the ground state(or low-energy) structures. To take some distortions into account I would need larger supercell than others.
I know that we cannot directly compare the total energies of two structures with different sizes due to the problem of k-points. However, is there any good ways to do this?
Let's say I have two supercells, one is 2x2x4 and the other is sqrt(2)xsqrt(2)x4. Surely I can contain the same distortion patterns of sqrt(2)xsqrt(2)x4 cell in the 2x2x4 cell, but if there is a way to reduce the cost of time, that would be excellent. I am not sure how can I make their k meshes equivalent in this case...
Thanks,
Yuanjun