Yambo Community Forum

Dear all,

1、For two-dimensional materials, a cutoff needs to be added. I am still somewhat confused about the size of the CutBox. Suppose there is a two-dimensional material with a vacuum layer in the z direction. The thickness of the material is 5 Å (~9.4 a.u.), and the thickness of the vacuum layer is 20 Å (~37.74 a.u.). Therefore, the lattice size along the z direction is 9.4 + 37.74 = 47.14 a.u. When setting the cutbox size, it should be slightly smaller in the z direction. Should I set it slightly smaller than 37.74, for example, 35? Or should I set it slightly smaller than 47.14, for example, 45?

2、When I set

| CUTGeo= "slab z" # [CUT] Coulomb Cutoff geometry: box/cylinder/sphere/ws/slab X/Y/Z/XY..
| % CUTBox
| 0.00000 | 0.00000 | 35.00000 | # [CUT] [au] Box sides

after the calculation is completed, the end of the file r-HF_and_locXC_gw0_dyson_rim_cut_em1d_ppa_el_el_corr shows

| CUTGeo= "slab z" # [CUT] Coulomb Cutoff geometry: box/cylinder/sphere/ws/slab X/Y/Z/XY..
| % CUTBox
| 0.00000 | 0.00000 | 0.00000 | # [CUT] [au] Box sides

Why does this happen? When I set box z, it works normally, but I was previously informed that box z has been deprecated and is no longer used.

Thank you in advance for your help.

Best,
sunxl

Dear Sunxl,

Yes, it is suggested to use the slab geometry as it is analytical.
CUTBox variables are used in the "box" geometry, so it is not needed for the "slab". The slab geometry does not require other input variables, and this is why the value of this variable in the input is not read.

Best.
Daniele