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A1 Friction

The assignment introduces the LAMMPS environment for running molecular dynamics (MD) simulations, focusing on input and output files. Students are required to run simulations, modify parameters such as simulation time and volume, and analyze generated log and dump files. Submission must include input scripts, simulation snapshots, and log files in a consolidated PDF document.

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Vedant Yadav
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21 views2 pages

A1 Friction

The assignment introduces the LAMMPS environment for running molecular dynamics (MD) simulations, focusing on input and output files. Students are required to run simulations, modify parameters such as simulation time and volume, and analyze generated log and dump files. Submission must include input scripts, simulation snapshots, and log files in a consolidated PDF document.

Uploaded by

Vedant Yadav
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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MM 722 Assignment 1 Autumn 2025

Assignment 1: Today’s assignment will introduce you to the LAMMPS environment and various input
and output files. By the end of session, you should know how to run a MD program in LAMMPS and
the kind of output that is generated by a MD program.

This assignment has the following components,

1. Go to the LAMMPS folder (you will know the exact location in class) and examine the various
directories that form the part of the code. (Discussion in class)

2. Your assignment directory (MM 722 A1) will be on the desktop and you should copy the
LAMMPS executable file from the LAMMPS directory to the assignment directory.

3. Take some time to go through the input script (the most important file which contains
commands to run the LAMMPS MD simulation). This file simulates frictional contact between
two asperities at the nanoscopic level.

4. Run the code by using the command - ./lmp_serial < in.friction

5. Several files are created when you execute the command. What are these files? What do they
represent?

a. Log file: contains the log of the execution


b. Dump file: output from the MD simulation – go through the file carefully and
understand this.

Problem 1: Run the simulation for a different length of time.

Problem 2: Change the size of the simulation volume and run the simulation again. Specifically,
increase the length along the x-axis and include more than one asperity each on the two surfaces.
For instance, you can try to include two asperities on the bottom (or top) and one on the top (or
bottom) surface. You can include two asperities each on both surfaces, too! Try to play with the
region command and see if you can achieve this.

Problem 3: (Bonus) Can you change the frequency of output of the simulation? You can go to the
LAMMPS manual page online (or through the local LAMMPS directory) and see the manual page
for the dump command.
Attempt to change the frequency of output.

Note on submission (important)


Please include the following in your submission. Submission should be in the form of ONE
consolidated pdf document.
i. Input scripts for the changes you made. They should be in the format, “in.friction_P1” for
input script for problem 1.
ii. Simulation snapshots showing the modified simulation volumes from problem 2. Use
appropriate file names for describing your files. iii. Log files showing th change in frequency of
output from problem 3, e.g., log.lammps_P3_a.

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