I want to calculate the melting point for tip4p.with plot of energy versus time
- I have used this paper (The melting point of ice Ih for common water models calculated from direct coexistence of the solid-liquid interface) for comparing the results.there is a big difference between total energies. I have used total energy of system that calculated with thermo_style command.
The order of energies of mine is 1000 Kcal/mol, but theirs is 10 Kj/mol.(I have attached my results and my input file) . when I use the thermo_modify norm yes,The order of energy is more logical, but it is not correct yet(file is attached). My method for determining the melting point is it true?
- I have used npt ensemble and p=1 (unit real) and constant temperature. It is been seen that the pressure fluctuates widely.(pressure file is attached ). I have used pchain and tchain and drag commands for solving the fluctuation, but it did not work.
Could you help me with these problem,please?
etotal.txt (211 Bytes)
input.in (2.43 KB)
I want to calculate the melting point for tip4p.with plot of energy
versus time
why? there are much better methods to do this.
1) I have used this paper (The melting point of ice Ih for common water
models calculated from direct coexistence of the solid-liquid interface)
this paper is using one of them.
for comparing the results.there is a big difference between total
energies. I have used total energy of system that calculated with
thermo_style command.
in all likeliness they will be different. please explain why you think
they should be the same and what you did when setting up your system to
The order of energies of mine is 1000 Kcal/mol, but theirs is 10
Kj/mol.(I have attached my results and my input file) . when I use the
thermo_modify norm yes,The order of energy is more logical,
this has nothing to do with logic but rather with normalization. it looks
like you have some serious conceptual difficulties with this and i strongly
suggest you discuss this with your adviser and your colleagues.
particularly let somebody explain to you the difference between intensive
and extensive properties.
but it is not correct yet(file is attached). My method for determining
the melting point is it true?
your method is bad for many reasons.
2) I have used npt ensemble and p=1 (unit real) and constant temperature.
It is been seen that the pressure fluctuates widely.(pressure file is
attached ). I have used pchain and tchain and drag commands for solving the
fluctuation, but it did not work.
Could you help me with these problem,please?
this topic has been discussed on this very mailing list only a gazillion
times. please dig through the archives.
Dear Axel
I looked at mailing list, but I can not find an appropriate solution.
Dear Axel
I looked at mailing list, but I can not find an appropriate solution.
you didn't look well enough. ....and you have a paper *using* a better
solution right in front of you.
yes. they use from this method:
The velocity at which the interface boundary moves as a
function of deviations from the equilibrium melting tempera-
ture is usually termed the interface response function.
I do not know how to do it with lammps. I looked for it . but I did not answer in lammps users.
I’m not sure what you are asking. Possibly
that you want to track the interface between a liquid
and solid automatically? For a crystalline system
(e.g. a metal lattice) you can often do this by
monitoring the local order around each atom. E.g.
computes like compute centro/atom or compute cna/atom
or even compute coord/atom. But for a molecular
crystal like ice, I think you will need to post-process
dump files and figure out the location of the interface
from each snapshot.
Steve