TiAl structure optimisation

TODO Write some text motivating this example

Setup system:

## TODO: Should run as @example once EmpiricalPotentials is compatible with AB 0.5
using AtomsIO
using EmpiricalPotentials

system = load_system(joinpath(pkgdir(EmpiricalPotentials), "data/TiAl-1024.xyz"))
nothing

Setup calculator:

## TODO: Should run as @example once EmpiricalPotentials is compatible with AB 0.5
using Unitful
using UnitfulAtomic

calc = LennardJones(-1.0u"meV", 3.1u"Å", 13, 13, 6.0u"Å")
nothing

Minimise energy:

## TODO: Should run as @example once EmpiricalPotentials is compatible with AB 0.5
using GeometryOptimization
GO = GeometryOptimization

results = minimize_energy!(system, calc, GO.OptimCG(); maxiters=10, verbosity=1)
results.energy

Final structure:

## TODO: Should run as @example once EmpiricalPotentials is compatible with AB 0.5

results.system