Getting started with LAMMPS

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What is LAMMPS?

LAMMPS is a classical molecular dynamics code with a focus on materials modeling. It’s an acronym for Large-scale Atomic/Molecular Massively Parallel Simulator.

LAMMPS has potentials for solid-state materials (metals, semiconductors) and soft matter (biomolecules, polymers) and coarse-grained or mesoscopic systems. It can be used to model atoms or, more generically, as a parallel particle simulator at the atomic, meso, or continuum scale.

Install LAMMPS:

Windows: https://rpm.lammps.org/windows/64bit/

Here choose the first package and download it:

Screenshot of the page

Linux: https://docs.lammps.org/Install_linux.html

Now.... Let's download VScode.

Go here: https://code.visualstudio.com/

Download and install it.

Then... Click on Extensions(The Rubik's cube like icon):

The tab is called Extensions

On the Search Box type: lammps

You'll get these two:

Install the first one which says: Lammps Syntax...

Now you're ready to fly!!!

What to do after these?

Take a long breath & go here: https://lammpstutorials.github.io/index.html

Choose one and click it.

Here I've chosen the first one:

Read the Getting Started and go to The input script section. Here we're skipping the installation step as we've already done that.

You'll see:‌

Here the grayed area has codes or commands. Commands are to be run on the LAMMPS shell or terminal of VScode.

Now... let's create a input.lammps file in VScode by clicking File on the upper left and choosing New File. Here I've created the file inside a folder titled "lammps". Now copy and paste the below lines:

# Initialization
# System definition
# Simulation settings
# Run

# -------------	Initialization
units		lj
dimension 	2
atom_style	atomic
pair_style	lj/cut 2.5
boundary	p p p

Each LAMMPS script has four steps:

a. Initialization

b. System Definition

c. Simulation Settings

d. Run

In this tutorial I'll only write the Initialization step.

If you hover on the code, for example here if I hover on units you'll see it's use and examples:

Explanation of codes

Now.... Let's open the terminal:

Click on the upper left Terminal or press
ctrl + shift + `

You'll get this in the bottom:

Type lmp here and hit enter

If you get something like below:

Then LAMMPS is succesfully installed. Else try reinstalling LAMMPS & try again.

Hit ctrl + c

Now type the below lines in the terminal and hit enter:

lmp -in input.lammps

Your terminal will look like this:

Congo!!! You've just run your first LAMMPS code!

Explore https://lammpstutorials.github.io/tutorials/01-SimpleMolecularSimulation.html to finish the code.

Examples:

1. https://lammpstutorials.github.io/index.html

2. LAMMPS documentation: https://docs.lammps.org/Manual.html

References:

a. https://www.lammps.org/

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