Could someone please help by providing the inputs for LAMMPS systems in which ionic liquid (such as EMIM) and solid substrate are used?
I would like to train in the use of molecular dynamics techniques.
Altaf Hussain Siraj
Input files without discussion are next to useless as training materials.
That said, there are plenty of input files in the “examples” folder of the LAMMPS source code distribution.
You need to pay attention to the README files and the corresponding documentation in the manual.
But note that those examples were mostly created to just demonstrate the usage of certain commands in context and provide short tests, NOT to be suited for teaching good simulation practices.
Thus I suggest training with materials that were created specifically for that purpose. Try
Some older materials are linked here: https://www.lammps.org/tutorials.html
and please also note the recorded videos from the last LAMMPS Workshop.
As a starting point, you should look at the literature coarse grained force fields of Roy and Maroncelli for EMIm-BF4 and BMIm-PF6 (which are used extensively by the Salanne group) and their modern update by Bresme et al. for CnMIm cations.
These will equilibrate fairly quickly and get you used to implementing and validating a force field (generate initial configuration, equilibrate in NPT and NVT, and compare densities and radial distribution functions against both experimental and computational references at multiple temperatures). You will also have to convert units for LJ potentials, use PPPM long range coulombic solvers (and specify their accuracy), and apply SHAKE for rigidifying molecules.
Once you are confident with this you can then incorporate carbon-planar surfaces, and again there are many literature references that you can aim to validate, especially for the Roy-Maroncelli force field as applied in works around 2013 and onwards. You should pay attention to how you can build a nanopore / nanoslab with a solid-IL interface, including applying non-periodicity perpendicular to the slab, and how you can be sure it matches your desired pressure, because naively applying a piston pressure on your surfaces will not always work (you can try it but you will see why).
When you have a clear picture of what you are trying to achieve, physically and mathematically, it is not too difficult to write a simulation script for LAMMPS. On the other hand if you become unclear on what you are trying to achieve, but simply use a script from somewhere else, you are at the mercy of whoever wrote that script and any errors they may have made (and I have made many myself!!!).
All the best,