Optimization of MoS2 structure

[Elio]

Dear all,

I am trying to optimize the structure of monolayer MoS2 using Elk; however I keep on getting the error:

rror(checkmt): muffin-tin radius too small for species 2 (S)
Radius : -0.5000000000E-01

Is that due to he geometry /positions of the atoms? This structure is giving me a hard time.

The input is:

tasks
2

! lattice vector optimisation while maintaining the unit cell volume
! speed the calculation up with Broyden mixing
mixtype
3

ngridk
8 8 8

avec
1.000000000 0.000000000 0.000000000
-0.500000000 0.866025400 0.000000000
0.000000000 0.000000000 6.50000000

! decrease the unit cell volume to increase the pressure
scale
5.896

latvopt
2

autoswidth
.true.

tforce
.true.

epsengy
1.e-7

epspot
1.e-6

epsforce
2.e-3

stype
0

xctype
2

rgkmax
8

gmaxvr
16

sppath
'/home_cluster/fis718/eliemouj/elk-3.0.18/species/'

atoms
2 : nspecies
'Mo.in' : spfname
1 : natoms; atpos, bfcmt below
0.00000000000 0.00000000000 0.00000000000 0.00000000 0.00000000 0.00000000
'S.in' : spfname
2 : natoms; atpos, bfcmt below
0.60000000000 0.00000000000 1.000000000000 0.00000000 0.00000000 0.00000000
0.60000000000 0.00000000000 -1.0000000000 0.00000000 0.00000000 0.00000000

thanks in advance

Elio
University of Rondonia
Brazil

[Vitaliy Romaka]

The atomic position of the second atom doubles the first one. You have two atoms in the same position. The geometry seems to be wrong, cause -1 and 1 are the same coordinstes within the periodic lattice

[Elio]

Dear Romaka,

Thanks for pointing out this to me. It might be better to use the spacegroup utility to generate the atomic positions then. Any source of where I can find the Wyckoff coefficients to plug in the spacegroup.in input file?

[Vitaliy Romaka]

Dear Elio,
International tables, volume A, or some nonfree software lime Diamond.
However, as far as Iknow there is no need to know wyckoff coefs.to prepare geometry in spacegroup utility. You need only atomic coordinates of atoms in the assymetric part of the unit cell.