[lammps-users] error on units box

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1

29.05.2010 23:50, Romashevsky S. пишет:

2

29.05.2010 23:50, Romashevsky S. пишет:

here my example:

lattice fcc 0.65
region box block 0 15 0 10 0 6 units box
create_box 2 box
create_atoms 1 box units box

i use box to define a simulation box in the create_box command, not the
region.

but the problem is still actual. LAMMPS gives me an error:

of course you are getting an error. you should get one.
have a look at the melt example. that is how you should do it.
note hat the commands you are using have defaults for units
and if you change from lattice to box, it should change.
from the energies below it looks as if you are placing atoms
(almost) on top of each other. GIGO.

axel.

3

i've looked at the melt example, here it is:

lattice fcc 0.8442
region box block 0 10 0 10 0 10
create_box 1 box
create_atoms 1 box
mass 1 1.0

but if i do like this, i'll get the result that i've had before:

4

2010/5/29 Romashevsky S. <[email protected]...>:

i've looked at the melt example, here it is:

lattice fcc 0.8442
region box block 0 10 0 10 0 10
create_box 1 box
create_atoms 1 box
mass 1 1.0

but if i do like this, i'll get the result that i've had before:

---------------------------------------------

lattice fcc 0.65
Lattice spacing in x,y,z = 1.83252 1.83252 1.83252
region box block 0 15 0 10 0 6 #units box
create_box 2 box
Created orthogonal box = (0 0 0) to (27.4878 18.3252 10.9951)
1 by 1 by 1 processor grid
create_atoms 1 box #units box
Created 3600 atoms

Memory usage per processor = 1.97637 Mbytes
Step Temp E_pair E_mol TotEng Press
0 1 0 0 1.2745833 0.55231944
1000 1.0001116 -0.66672254 0 0.60800304 3.0162623
2000 1 -0.69677192 0 0.57781141 2.8832454

------------------------------------------------------------

but i want to have orthogonal box (15 10 6), not (27.4878 18.3252 10.9951).

the region is in multiples of the lattice spacing, so all
you have to do is to divide those values by 1.83252.

but if you want a "proper" fcc crystal, you cannot have 15 10 6,
since each length has to be a multiple of lattice vector components.
you would have to adjust the lattice constant to give you a 1.0 1.0 1.0
vector. fairly obvious, isn't it?

cheers,
   axel.