To compare the Nose hover thermostats with DPD thermostats

Dear LAMMPS-Users,

I am trying to do a simple test to compare the effects of “Nose-Hoover” thermostats with “DPD” thermostats on my model. In my model, I am simulating water transport through CNT.

To this aim, I applied “fix nvt” to perform time integration on Nose-Hoover thermostats. I also used “pair_style lj/cut/coul/long 10.0 10.0” in conjunction with that to do force field interaction.

To apply DPD thermostats I am not sure how can I use it correctly in my script?
Because, by referring to mailing list archive I found that the experts at this link (http://lammps.sandia.gov/threads/msg38906.html) commented that we can not use “fix nvt” with “pair style dpd” at a same time. But, when referring to the dpd doc page at (http://lammps.sandia.gov/doc/pair_dpd.html) it has mentioned that " This pair-wise thermostat can be used in conjunction with any pair style, and in leiu of per-particle thermostats like fix langevin or ensemble thermostats like Nose Hoover as implemented by fix nvt".

Regarding to my poor MD knowledge, if we want to use “DPD” thermostats with out “fix nvt” how would be able to do time integration?

I also did a small test by applying “dpd” with no “fix nvt” to see the thermodynamics quantities . But, the values are not changed. Please take a look at below

Step Temp PotEng TotEng Press Volume

100 251.80521 8.2848811e-07 2681.8348 3405.0472 36000
200 251.80521 8.2848811e-07 2681.8348 3411.3199 36000
400 251.80521 8.2848811e-07 2681.8348 3404.1397 36000
600 251.80521 8.2848811e-07 2681.8348 3402.0207 36000
800 251.80521 8.2848811e-07 2681.8348 3394.0435 36000
1000 251.80521 8.2848811e-07 2681.8348 3398.1949 36000
1100 251.80521 8.2848811e-07 2681.8348 3412.1816 36000

I would be greatly appreciated if anybody guides me how I can apply dpd thermostats properly.

Dear LAMMPS-Users,

I am trying to do a simple test to compare the effects of "Nose-Hoover"
thermostats with "DPD" thermostats on my model. In my model, I am simulating
water transport through CNT.

To this aim, I applied "fix nvt" to perform time integration on Nose-Hoover
thermostats. I also used "pair_style lj/cut/coul/long 10.0 10.0" in
conjunction with that to do force field interaction.

To apply DPD thermostats I am not sure how can I use it correctly in my
script?
Because, by referring to mailing list archive I found that the experts at
this link (http://lammps.sandia.gov/threads/msg38906.html) commented that we
can not use "fix nvt" with "pair style dpd" at a same time. But, when
referring to the dpd doc page at
(http://lammps.sandia.gov/doc/pair_dpd.html) it has mentioned that " This
pair-wise thermostat can be used in conjunction with any pair style, and in
leiu of per-particle thermostats like fix langevin or ensemble thermostats
like Nose Hoover as implemented by fix nvt".

Regarding to my poor MD knowledge, if we want to use "DPD" thermostats with
out "fix nvt" how would be able to do time integration?

your problem is not exactly due to poor MD skills, but rather due to
poor reading skills. if you read the sentence directly before and the
one directly after the text you quoted, you have your answer: this
segment refers to pair style dpd/tstat and not dpd and you need to use
it in combination with the hybrid/overlay pair style.

I also did a small test by applying "dpd" with no "fix nvt" to see the
thermodynamics quantities . But, the values are not changed. Please take a
look at below

Step Temp PotEng TotEng Press Volume

     100 251.80521 8.2848811e-07 2681.8348 3405.0472 36000
     200 251.80521 8.2848811e-07 2681.8348 3411.3199 36000
     400 251.80521 8.2848811e-07 2681.8348 3404.1397 36000
     600 251.80521 8.2848811e-07 2681.8348 3402.0207 36000
     800 251.80521 8.2848811e-07 2681.8348 3394.0435 36000
    1000 251.80521 8.2848811e-07 2681.8348 3398.1949 36000
    1100 251.80521 8.2848811e-07 2681.8348 3412.1816 36000

I would be greatly appreciated if anybody guides me how I can apply dpd
thermostats properly.

sorry, but - as has been repeatedly pointed out - this mailing list is
not a classroom. find yourself a proper tutor. given your difficulties
to teach yourself from the available tutorial and documentation
material, there really is no alternative and no hope to get any
meaningful simulations done. without the personal tutoring and
feedback from somebody with MD experience, you are likely to make many
mistakes and errors, often without even noticing.

axel.

Once you turn-off fix not and use dpd/tstat, you need
to use fix nve to integrate the atoms. W/out that
the atoms won’t move and that’s why the temperature
isn’t changing.

Steve