Add initial Docker setup. (#56)

Dockerfile

@@ -0,0 +1,30 @@
+FROM ubuntu:22.10
+
+# build-essential is needed for building the C++ code in the PPAFM package
+
+RUN apt-get update --yes &&                       \
+    apt-get install --yes --no-install-recommends \
+    build-essential                               \
+    python3                                       \
+    python3-pip                                   \
+    python-is-python3 &&                          \
+    apt-get clean && rm -rf /var/lib/apt/lists/*
+
+RUN useradd -ms /bin/bash ppafm-user
+
+RUN mkdir /exec && chown ppafm-user:ppafm-user /exec
+
+USER ppafm-user
+
+WORKDIR /home/ppafm-user
+
+RUN pip install --upgrade --user pip && pip cache purge
+
+COPY --chown=ppafm-user:ppafm-user ./ ppafm
+
+RUN pip install -e ppafm/ && pip cache purge
+
+
+ENV PATH="${PATH}:/home/ppafm-user/ppafm/"
+
+WORKDIR /exec

README.md

@@ -112,5 +112,22 @@ Hover the mouse cursor over any parameter for a tooltip explaining the meaning o
 * [Prokop Hapala, Georgy Kichin, Christian Wagner, F. Stefan Tautz, Ruslan Temirov, and Pavel Jelínek, Mechanism of high-resolution STM/AFM imaging with functionalized tips, Phys. Rev. B 90, 085421 – Published 19 August 2014](http://journals.aps.org/prb/abstract/10.1103/PhysRevB.90.085421)
 * [Prokop Hapala, Ruslan Temirov, F. Stefan Tautz, and Pavel Jelínek, Origin of High-Resolution IETS-STM Images of Organic Molecules with Functionalized Tips, Phys. Rev. Lett. 113, 226101 – Published 25 November 2014,](http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.113.226101)
 
+## Making ppafm platform-independent.
+
+We propose to use [Docker](https://docs.docker.com/get-docker/) to make the code platform-independent.
+
+Here are the steps to build and run the ppafm Docker container:
+
+1. Build the image.
+
+```bash
+$ docker build -t ppafm:latest .
+```
+2. Execute the container.
+
+```bash
+$ docker run --rm -it -v ${PWD}:/exec ppafm:latest <ppafm command>
+```
+
 ### License
 MIT

pyproject.toml

@@ -20,15 +20,15 @@ requires-python = ">=3.6"
 dependencies = [
     "ase",
     "matplotlib",
-    "numpy",
-    "pyopencl",
+    "numpy<=1.21.6", # Remove upper limit when #76 is fixed.
     "reikna",
 ]
 
 [project.urls]
 Homepage = "https://github.com/Probe-Particle/ProbeParticleModel"
 
 [project.optional-dependencies]
+opencl = ["pyopencl"]
 dev = [
     "pre-commit",
     "pytest",