Dear LAMMPS users,

I am trying to set up simulations of a crystal with triclinic box, I have the lattice parameters as a=8.05, b=13.04, c=19.48,

α =90, β =125.4 and γ=90. I have taken 4×2×4 system i.e., 4 unit-cells along X, 2 unit-cells along y and 4 unit-cells along Z.

now my cell dimensions has become x= 32.2 (4*8.05) , y= 26.08 and z=77.92, then I have calculated tilt factors based on relations xy= bcosγ = 0.0, xz=C*cosβ and YZ = b*c cosα- xy*xz/L_{y} = 0.0

I have specified these parameters in my input file as:

0.000 32.20 xlo xhi

0.000 26.08 ylo yhi

0.000 77.92 zlo zhi

0.00 -45.136 0.00 xy xz yz

With these setting I was not able to get the lattice parameters mentioned above, especially ( β =125.4). Up to few steps it has a value of 125.4 but then gradually reaching to 90.0,(Crystal structure is retaining in the simulations).

Actually my Xlo, Ylo and Zlo are not placed at origin, So then I have measured minimum and maximum co-ordinates along each direction and given those co-ordinates as input, in this case also I was unable to get the actual lattice parameters.

Can anybody please help me in this regard.

Thank you in advance.

Regards,

Ramesh.

Dear LAMMPS users,

I am trying to set up simulations of a crystal with triclinic

box, I have the lattice parameters as a=8.05, b=13.04, c=19.48,

α =90, β =125.4 and γ=90. I have taken 4×2×4 system i.e., 4

unit-cells along X, 2 unit-cells along y and 4 unit-cells along Z.

now my cell dimensions has become x= 32.2 (4*8.05) , y= 26.08 and z=77.92,

then I have calculated tilt factors based on relations xy= bcosγ = 0.0,

xz=C*cosβ and YZ = b*c cosα- xy*xz/Ly = 0.0

I have specified these parameters in my input file as:

0.000 32.20 xlo xhi

0.000 26.08 ylo yhi

0.000 77.92 zlo zhi

0.00 -45.136 0.00 xy xz yz

With these setting I was not able to get the lattice parameters mentioned

above, especially ( β =125.4). Up to few steps it has a value of 125.4

but then gradually reaching to 90.0,(Crystal structure is retaining in the

simulations).

Actually my Xlo, Ylo and Zlo are not placed at origin, So then I have

measured minimum and maximum co-ordinates along each direction and given

those co-ordinates as input, in this case also I was unable to get the

actual lattice parameters.

Can anybody please help me in this regard.

please (re)-read the documentation about limitations to the tilt

factors and box flips.

http://lammps.sandia.gov/doc/Section_howto.html#howto_12

http://lammps.sandia.gov/doc/fix_deform.html

axel.