I want to do strain calculations for Au nanoparticles. How can I do this in Lammps? I would appreciate your suggestions.
Hi, if you have some specific question regards using the software, you can also post in the LAMMPS forum site. Process would be to create the substrate of nanoparticles and applying strain (tensile or compressive) using various commands in LAMMPS.
There are a lot of things that you can do appart of adding some pressure (hydrostatic or uniaxial) to the system etc
For example you can also move or displace some atoms and then follow how them, or neigbours, in their time evolution. In general you can evaluate the forces, strains etc acting in any particular atom or grupo of atoms etc.
Look also in the LAMMPS users website. can be very usefull
Shahid, for bulk materials which span the periodic box, it is not difficult to perform stress-strain calculations. LAMMPS has a command, "fix deform", which enables you to change the shape of the simulation box over time. All that is left is to output the pressure tensor in your simulation thermodynamics.
However, since you are working with nanoparticles, I am not sure which forces you are interested in. For example, are you putting a strain within each nanoparticle? Or are you looking at interparticle forces? Depending on the answer, that will influence the techniques required. In the former case, putting a strain on a nanoparticle would require some experimental design on your part to define which atoms are being pulled etc.
In addition to the Josh's comment, you should use fix nvt to account for the contribution of the kinetic term, if you deform your structure at finite temperature.
For strain calculation in LAMMPS, perform a tensile testing simulation of a cylindrical Au nanoparticle. FIxed some portion at both ends of the cylindrical nanoparticle and apply velocity to the upper end. Calculate the strain from the displacement of the center of mass of the movable part.
You can also refer to these works:
Article Study of the effect of varying core diameter, shell thicknes...
Article Non-equilibrium MD modeling and simulation to extract mechan...
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