The equation 2 in document is different with the published version

[fangrh]

Hi,

When I learn the theoritical background of the documentation, I found that the equation 2 describe the Poisson equation is different with the version of the arxiv version.

[loganbvh]

In the arxiv version, the vector potential A is assumed to be time-independent. After the paper was published/put on arxiv, I implemented time-dependent vector potential as described in the online documentation.