Christoph Ortner

There could also be an ``` energy_forces_virial(atoms, calc)::Tuple{...} ``` to compute everything at the same time, that way we don't need to cache things.

calculator (ASE language). It's the object the calculates things. The potential, etc...

``` forces(atoms, calc; kwargs...)::AbstractVector{

> I think system information is required, not just atoms, since the boundary will be required sure `atoms` = system in almost every package I know hence I used that...

> In my opinion, not having concrete type in the definition is the best here too. There is no definition since we are just providing the prototypes. There is only...

I'm ok with that but how can it be part of the definition? It can only be part of the documentation?

Something like that would be nice.

I would be very happy with that, but didn't want to go overboard on a first PR. But it doesn't hurt to put it into the mix. With that we...

What about having a generic function ```julia calculate(property::Symbol, system, atoms) ``` and or even allow multiple properties. The functions above could then just be treated as syntax sugar.

I disagree. 2. It doesn't have to be type-unstable if we replace `Symbol` with something else. For example, ```julia calculate(PotentialEnergy, system, calculator) ``` where `PotentialEnergy` is a singleton type. 1....