Update on installation of SLLOD with npt?

[Swarnendu]

Hello everyone,

I want to use sllod with npt thermostat. There seems currently no direct way to use it in lammps. I went through the following thread and it looks like there was some effort.

Some observations about SLLOD

Hello Users and Developers, I have recently been looking into the SLLOD implementation with interest in making a new “fix” which will integrate the SLLOD equations in the NPT ensemble (of type “iso”) and I noticed some details about the current implementation which I though were worth mentioning. I think there might be a small inconsistency in the SLLOD code as well, so if you are interested only in that, please skip to 2. The current version of SLLOD is thermostat driven, which causes oscill…

But this was in 2013. Is there any update on that since then?

PS: As per my personal interest, I want to shear the system [point particles in 3d] (using fix/deform) with something like “npt/sllod”, when the volume change is isotropic.

[akohlmey]

@Swarnendu

But this was in 2013. Is there any update on that since then?

Any feature available in LAMMPS is documented. If there is no documentation for it, the feature does not exist (in the LAMMPS distribution). It is a simple as that.

Many people have written that they are looking into implementing a feature into LAMMPS and even more have done so. However, only a subset of those actually submit their code for inclusion into LAMMPS. There is no way to force them to do so, only a moral obligation (you get LAMMPS for free, so you pay the LAMMPS community back with improving it). I can only speculate about the reasons. The only thing I can say for certain is that the LAMMPS developers do not pay attention to that. We are too busy just keeping things going as it is.

Feel free to try contact the original poster (which is not likely to work after such a long time), but chances are, you won’t get the feature you are looking for. The only way to get it then is to either implement it yourself or find a collaborator that is willing and able to do so.

[jtclemm]

@Swarnendu

I want to shear the system [point particles in 3d] (using fix/deform) with something like “npt/sllod”, when the volume change is isotropic.

I don’t understand what you mean by “something like,” but if fix deform is sufficient for applying shear then you might want to look at fix deform/pressure which also includes barostats. However, instead of Nose Hoover (is that required?) it uses a linear controller: fix deform/pressure command — LAMMPS documentation.

Simple shear can be combined with a barostat that isotropically changes the box volume using:
fix 1 deform/pressure 1 xy erate ${rate} box pressure ${targetpressure} ${gainconstant}

The erate/rescale option may also be important, as well as max/rate and normalize/pressure.

That being said, I don’t know your actual requirements.