Obtaining PSI4¶

How to obtain Psi4: start with find-the-code quiz, end in `{top-level-psi4-dir}`¶

A better decision tree is available at psicode.org/installs/latest, though the below remains valid.

Take a quiz to find the best version of the codebase for your needs, be it binary, tarball, or version-controlled repository. Or, select outright among:

Binary Installer
Conda Binary Package
Clone from GitHub Repository
Fork from GitHub Repository (only path to develop PSI4)
Tarball from GitHub Repository
Psi3 from SourceForge

Find-the-code Quiz¶

A better decision tree is available at psicode.org/installs/latest, though the below remains valid.

I just want to run the code. I may tweak the Python, but I’m not developing anything to contribute back to the code base.
- Provided I still get good, threaded BLAS/LAPACK, OpenMP parallelism, and optimization for a variety of processor architectures (except Mac, which is least common denominator), I’m willing to forgo architecture tuning wizardry to avoid compiling it myself.
  - I’m on Linux or Mac or Windows with Ubuntu Bash Shell.
    - I’m familiar with conda and want to manage PSI4 as an ordinary conda package. — Goto Binary-Package
    - I just want a PSI4 installer. — Goto Binary-Installer
- I want to compile it myself to eke out best performance on my computer. I accept responsibility for navigating compiler, threading, and BLAS/LAPACK compatibility
  - I’m willing to have minimal dealings with git (e.g., commands git clone and git pull) in return for easy access in future to new features and bug fixes. — Goto Clone-from-GitHub
  - I don’t want to deal with this newfangled git, just give me a tarball of the source code — Goto Tarball-from-GitHub
I want to run and develop in PSI4.
- In keeping with the open-source philosophy, I don’t mind my code being as public as Psi4 itself during the development process. — Goto Fork-from-GitHub
- I want to develop using PSI4 infrastructure and libraries, not on them; I think a plugin might do.
  - I’ve got a PSI4 compilation. Use it, then consult plugins
  - I’d rather not compile PSI4 or I don’t have compilers — Goto Binary-Package then consult plugins through conda
I really like parentheses and/or DBOC, so I want Psi3. — Goto Psi3-from-SourceForge

Binary Installer¶

Get Initially

Just go to http://www.psicode.org/downloads.html and follow the instructions there.
Build

Not applicable as binary is pre-built.
Get Updates directions
```
>>> conda update psi4
```
Contribute Back

Not applicable as not under git control.

Conda Binary Package¶

Get Initially

The pre-compiled conda packages at https://anaconda.org/psi4/psi4 can be installed into an existing Anaconda or Miniconda distribution according to directions. Locally, install into a conda environment as below.
```
>>> conda create -n p4env psi4 -c psi4
>>> conda activate p4env
```
Build

Not applicable as binary is pre-built.
Get Updates directions
```
>>> conda update psi4 -c psi4
```
Contribute Back

Not applicable as not under git control.

Clone from GitHub Repository¶

Get Initially

The PSI4 repository at https://github.com/psi4/psi4 works like every other GitHub repo. Locally, clone as below.
```
# use https or ssh
>>> git clone https://github.com/psi4/psi4.git
>>> cd psi4
# this is your {top-level-psi4-dir}
```
Build directions

Get Updates

# on branch master
>>> git pull origin master

Contribute Back

Contributions cannot be made directly to the main repository. Fork instead.

To convert clone to fork, go to https://github.com/psi4/psi4, and hit the Fork button to store a PSI4 repository in your GitHub account.
```
>>> git remote rename origin upstream
>>> git remote add origin https://github.com/johndoe/psi4.git
```

Fork from GitHub Repository¶

Get Initially

Go to https://github.com/psi4/psi4, and hit the Fork button to store a PSI4 repository in your GitHub account. Locally, proceed to clone:
```
# replace johndoe
# use https or ssh
>>> git clone https://github.com/johndoe/psi4.git
>>> cd psi4
# this is your {top-level-psi4-dir}
```
Set up a connection between your forked repository and the parent repository.
```
>>> git remote add upstream https://github.com/psi4/psi4.git
```
Build directions
Get Updates

Locally, update your fork from the parent repository and store on GitHub at your fork.
```
# on branch working_branch
>>> git pull --rebase upstream master
>>> git push origin working_branch
```
Remember: Working in the master branch of a fork is considered bad practice.
Contribute Back

PSI4 contributions process here and here. Consider preparing your contribution in a branch then issue a GitHub pull request.

Tarball from GitHub Repository¶

Get Initially

Discouraged! From the PSI4 repository at https://github.com/psi4/psi4, hit the “Clone or download” then “Download ZIP” button. Locally, unpack as below.
```
>>> unzip psi4-master.zip
>>> cd psi4-master
# this is your {top-level-psi4-dir}
```
Build directions
Get Updates

Download new tarball and rebuild.
Contribute Back

Not applicable as source not under git control.

Psi3 from SourceForge¶

Get Initially

A tarball of the most recent version of Psi3 (3.4.0 circa 2009) is available from SourceForge
Build

Follow the INSTALL file that comes with the distribution. An old computer is probably handy for generating a working executable.
Get Updates

Updates are not forthcoming.
Contribute Back

This code is not under any development.