NVE calculation

Dear authors and LAMMPS user 

I want to equilibrate a (10,10) carbon nanotube system with NVE and want to check whether it is equilibrated or not. For this input files are: data.swnt1 and in.input1 and output files: log.lammps

By seeing the log file I can see that the energy is not changing at all. Its value is fixed. What I expect is initially for few time steps, the energy will vary and then as time goes on, energy will reach to some constant value ( may be a small oscillation in it). But the energy don’t change at all. So may I request you to kindly tell me how to equilibrate a system. Att the files I have attached with this email.

Thanking you

Sincerely yours

Rajkumar Mondal,

Dept of Physics,

Assam University,

Silchar


in.input1 (812 Bytes)

data.swnt1 (107 KB)

log.lammps (55.2 KB)

Dear authors and LAMMPS user

I want to equilibrate a (10,10) carbon nanotube system with NVE and want
to check whether it is equilibrated or not. For this input files are:
data.swnt1 and in.input1 and output files: log.lammps

By seeing the log file I can see that the energy is not changing at all. Its
value is fixed. What I expect is initially for few time steps, the energy
will vary and then as time goes on, energy will reach to some constant value
( may be a small oscillation in it). But the energy don't change at all. So
may I request you to kindly tell me how to equilibrate a system. Att the
files I have attached with this email.

your atoms are practically not interacting (see E_pair) , so why
should there be much of a change in the structure and thus relaxation?
MD follows the GI-GO principle, i.e. garbage in, garbage out. use a
more meaningful model and parameters and you'll see a more meaningful
behavior.

this is not about equilibration, but about bad input.

If you dump forces you will see they are all tiny (10-12).

My guess is your epsilon value of 0.00284 is far too small

for meaningful interactions between atoms. Possibly

the cutoff is also too small, i.e. almost no pairs are interacting,

Steve

2015-03-05 15:40 GMT+01:00 Rajkumar Mondal <[email protected]>:

Dear authors and LAMMPS user

I want to equilibrate a (10,10) carbon nanotube system with NVE and
want to check whether it is equilibrated or not. For this input files are:
data.swnt1 and in.input1 and output files: log.lammps

By seeing the log file I can see that the energy is not changing at all.
Its value is fixed. What I expect is initially for few time steps, the
energy will vary and then as time goes on, energy will reach to some
constant value ( may be a small oscillation in it). But the energy don't
change at all. So may I request you to kindly tell me how to equilibrate a
system. Att the files I have attached with this email.

the *total* energy doesn't change, at is should in NVE. the *potential*
energy does. However, your parameters seem bogus to me: a binding energy of
-6.9365844e-13 kcal/mol in a nanotube? That's impoossible, your LJ
parameters need fixing.

Kristof