A Python interface for ab initio path integral molecular dynamics simulations. i-PI is composed of a Python server (i-pi itself, that does not need to be compiled but only requires a relatively recent version of Python and Numpy) that apply an algorithm that updates the positions of the nuclei, and of an external code that acts as a client and computes the electronic energy and forces.
This is typically a patched version of an electronic structure code, but a simple self-contained Fortran driver that implements Lennard-Jones and Silvera-Goldman potentials is included for test purposes.
i-PI was originally developed to simulate the quantum mechanical nature of light nuclei by performing path integral molecular dynamics simulations, and it implements most of the state-of-the-art methods to accelerate this kind of calculations. It has since grown to also provide all sorts of simulation strategies, from replica exchange to geometry optimization.
To use i-PI with already existing drivers, install and update using Pip:
Last version::
python -m pip install git+https://github.com/i-pi/i-pi.git
Last Release::
pip install -U i-PI
Test with Pytest::
pip install pytest
pytest --pyargs ipi.tests
To develop i-PI or test it with the self-contained driver, follow these instructions. It is assumed that i-PI will be run from a Linux environment, with a recent version of Python, Numpy and gfortran, and that the terminal is initially in the i-pi package directory (the directory containing this file), which you can obtain by cloning the repository
git clone https://github.com/i-pi/i-pi.git
Source the environment settings file env.sh
as source env.sh
or . env.sh
. It is useful to put this in your .bashrc
or other settings file if
you always want to have i-PI available.
cd drivers/f90
make
cd ../..
This will first start the wrapper in the background, redirecting the output to
a log file, and then run a couple of instances of the driver code. The progress
of the wrapper is followed by monitoring the log file with the tail
Linux
command.
Optionally, you can make a copy of the directory with the example somewhere else if you want to keep the i-PI directory clean.
cd examples/tutorial/tutorial-1/
i-pi tutorial-1.xml > log &
i-pi-driver -h localhost -p 31415 -m sg -o 15 &
i-pi-driver -h localhost -p 31415 -m sg -o 15 &
tail -f log
The monitoring can be interrupted with CTRL+C when the run has finished (5000 steps).
The automatic test suite can be run by calling the i-pi-test script.
You need to have the pytest
package installed
i-pi-test
See more details in the README file inside the ipi_tests folder.
If you have new features you want to implement into i-PI, your contributions are much welcome.
See CONTRIBUTING.md
for a brief set of style guidelines and best practices. Before embarking
into a substantial project, it might be good to get in touch with the developers, e.g. by opening
a wishlist issue.