Documentation

README.md

@@ -1 +1,64 @@
-Picasso
+# Picasso
+
+Picasso is a performance portable library for particle-in-cell simulations
+which are utilized in application including plasmas physics and fluids and 
+solid mechanics. Picasso provides a range of interpolation schemes between
+particles and grids, both in order of the scheme and the type of scheme 
+(FLIP, APIC, PolyPIC), embedded free-surface tracking, extensive batched 
+linear algebra capabilties, as well as utilities for managing field data
+and simplifying on-node parallel execution.
+
+
+## Building Picasso
+
+### Dependencies
+
+Picasso's main dependency for building is [Cabana](https://github.com/ECP-copa/Cabana).
+The instructions for building Cabana can be found in the [Cabana wiki](https://github.com/ECP-copa/Cabana/wiki/1-Build-Instructions)
+In addition to the core Cabana dependencies of Kokkos and CMake, Cabana must 
+be built with the Cabana::grid library option turned on.
+
+Picasso Required Dependencies
+| Dependency |Required | Details |
+| ---------- -------- | ------  |
+|[CMake](https://cmake.org/download/)      | Yes     | Build system |
+|[Kokkos](https://github.com/kokkos/kokkos)    | Yes      | Portable on-node parallelism |
+|[Cabana](https://github.com/ECP-copa/Cabana) | Yes | Performance-portable particle and grid library |
+| ---------- -------- | ------  |
+
+In addition to these requried dependencies, the build of Cabana is required 
+to have certain options enabled. (Cabana::Grid, MPI?)
+
+There are additional optional dependencies for Picasso that depend on the 
+use case desired from Picasso or hardware type for the system building 
+Picasso.
+
+Picasso Optional Dependencies imported from Cabana
+| Dependency |Required | CMake Variable | Details | Required in or inherited from upstream dependency |
+| ---------- -------- | -------------- | -------  | ----- |
+|MPI | No | |Message Passing Interface | inherited from Cabana MPI build |
+| ArborX | No | Picasso_ENABLE_ARBORX |(Experimental) performance-portable geometric search (required for level-set) | N/A (is Cabana arborx entirely seperate from Picasso?)
+| HDF5 | No | (defined in Cabana?) | Particle I/O | inherited from Cabana build with HDF5 |
+| Silo | No | Picasso_ENABLE_SILO | Particle I/O | Cabana required to be built with SILO and Picasso built with SILO |
+| JSON | NO | (?) | JSON variable input |
+| GTest | NO | Picasso_ENABLE_TESTING |Unit test Framework | 
+| CUDA | NO | | Programming model for NVIDIA GPUs | Inherited from Cabana and Kokkos |
+| HIP | NO | | Programming model for AMD GPUs | Inherited from Cabana and Kokkos |
+| SYCL | NO | | Programming model for Intel GPUs | Inherited from Cabana and Kokkos |
+
+For Picasso-related questions you can open a GitHub issue to interact with the
+developers.
+
+## Contributing
+
+We encourage you to contribute to Picasso! Please check the
+[guidelines](CONTRIBUTING.md) on how to do so.
+
+## Citing
+
+If you use Picasso in your work, please cite the [JOSS article](CITATION.bib).
+Also consider citing the appropriate [release](https://doi.org/10.5281/zenodo.2558368).
+
+## License
+
+Picasso is distributed under an [open source 3-clause BSD license](LICENSE).