[lammps-users] the problem related with phase transition

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1

Dear Lammps users,

I have the problem related with phase transition. My file is attach.
can you help me.
Thanks in advance

phase transition.doc (247 KB)

2

If you're getting NaNs on timestep 0 in your thermo output,
then your system is not intialized correctly - e.g. it has
overlaps.

Steve

2009/7/28 ahmet yıldırım <[email protected]...>:

3

Hi,

I ran for16x16x16 region(N=4096 particle) and density=0.02. I dont have any problem. When I ran for 8x8x8 region(N=512 particle) Program is giving error.

I am getting “nans” after on timestep 0.

Step Temp TotEng Press Volume PotEng

0 1.9 4.6993414e+35 -1.8551831e+39 1333.3333 4.6993414e+35

100 nan nan nan nan nan

200 …

…
Dr.Roberto Berardi(works on liquid crystal) have got liquid crystal phase transition for N=512 and density=0.3 by monte carlo simulation but I dont obtain phase transition for N=512 and densitiy=0.3 by LAMMPS.

Thanks in advance

İnput file:

units lj

atom_style ellipsoid

lattice sc 0.02

region box block 0 16 0 16 0 16

create_box 1 box

create_atoms 1 box

set group all quat/random 982381

mass 1 1.5

shape 1 1 1 3

compute rot all temp/asphere

velocity all create 2.0 41787 loop geom

pair_style gayberne 1.0 3.0 1.0 4.0

pair_coeff 1 1 1.0 1.0 1.0 1.0 0.2 1.0 1.0 0.2 4.0

neighbor 0.3 bin

timestep 0.002

thermo_style custom step temp etotal vol epair press pe

thermo 100

fix 1 all npt/asphere 2.0 2.0 0.1 xyz 0.0 8.0 0.1

run 50000

unfix 1

fix 1 all npt/asphere 2.0 2.0 0.1 xyz 8.0 8.0 0.1

run 50000

28 Temmuz 2009 17:50 tarihinde Steve Plimpton <sjplimp@…24…> yazdı:

4

Your initial configuration is likely not correct, if the
timestep 0 energy is inifinite.

Steve

2009/7/30 ahmet yıldırım <[email protected]...>:

5

Hi,

Allrigt, how can I correct/adjust the initial configuration? can you help me

Thanks in advance

adlı kullanıcı şunu yazmış:

6

No - you have to setup a correct model for LAMMPS
to simulate it. It's unlikely anyone on the mail list
is going to help you learn MD. I'd suggset finding
a paper that does something similar to what you
want and starting with that.

Steve

2009/8/2 ahmet yıldırım <[email protected]...>: