Calculation of stresses with DFT

[Sanderosta]

Is your feature request related to a problem? Please describe. When using the ASE_OTF() class, the run_dft_par() function in the ase.dft module always requests forces, energies, and stresses. However, for some DFT calculators calculation of stresses can take a significant amount of time. Additionally, this restricts training to periodic structures.

Describe the solution you'd like It would be nice to have the option to pass an argument like "properties" as part of **dft_kwargs to the function, which would then be taken into account when requesting properties. This could save time when stresses are not used by the MD engine.

Describe alternatives you've considered I could create my own ase.dft module, which would not be too much work. However, this would not be an ideal solution.