include backbone vector in create_molecule

[1234somesh]

Added

• New optional argument backbone_vector enabling to build molecules along an input vector using pmb.create_molecule and pmb.create_pmb_object

[pm-blanco]

Overall, it looks good to me. However, we are missing a unit test to check this new feature. I suggest adding such unit test to testsuite/define_and_create_molecules_unit_tests.py. This unit test should create a molecule using pmb.create_molecule() with an input backbone_vector and check that the backbone of the corresponding molecule created in espresso follows the same vector as the input backbone_vector.

[pm-blanco]

The unit test looks good to me! Once you document the new optional argument backbone_vector in the list of args of the docstring of create_molecule and fix the issue with the additional columns in pmb.df, I think that we can merge this PR.

[pm-blanco]

Looks good to me. Congrats on your first successful PR @1234somesh!

[pm-blanco]

@kosovan @mariusaarsten here we have added the feature to create molecules along an input vector that you both needed for your projects.