Changed the uhf value when xtb calculates with lanthanides

[jonathan-schoeps]

The xtb calculation when lanthanides are present in the molecule now calculates with uhf = 0 to avoid shifting the uhf assignment to the ligands. When the xtb run is finished, the original uhf is reassigned to the molecule. This is linked to #50

[marcelmbn]

Have you checked these two aspects:

• The number of unpaired electrons with which xtb is started. You could also have a look at the command-line call
• Is the UHF value actually set back to the original value afterwards?

[jonathan-schoeps]

Have you checked these two aspects:

* The number of unpaired electrons with which `xtb` is started. You could also have a look at the command-line call

* Is the `UHF` value actually set back to the original value afterwards?

1. The command line call has no --uhf flag. And within each xtb run the unpaired electrons are 0.
2. The UHF value is correctly reassinged. The test was with this print statements:

def single_molecule_generator(
    config: ConfigManager,
    refine_engine: QMMethod,
    postprocess_engine: QMMethod | None,
    cycle: int,
    stop_event,
) -> Molecule | None:
    """
    Generate a single molecule.
    """
    if stop_event.is_set():
        return None  # Exit early if a molecule has already been found

    if config.general.verbosity == 0:
        # print the cycle in one line, not starting a new line
        print("✔", end="", flush=True)
    elif config.general.verbosity > 0:
        print(f"Cycle {cycle + 1}:")
    #   _____                           _
    #  / ____|                         | |
    # | |  __  ___ _ __   ___ _ __ __ _| |_ ___  _ __
    # | | |_ |/ _ \ '_ \ / _ \ '__/ _` | __/ _ \| '__|
    # | |__| |  __/ | | |  __/ | | (_| | || (_) | |
    #  \_____|\___|_| |_|\___|_|  \__,_|\__\___/|_|

    try:
        mol = generate_random_molecule(config.generate, config.general.verbosity)
    # RuntimeError is not caught here, as in this part, runtime errors are not expected to occur
    # and shall therefore be raised to the main function
    except (
        SystemExit
    ) as e:  # debug functionality: raise SystemExit to stop the whole execution
        if config.general.verbosity > 0:
            print(f"Generation aborted for cycle {cycle + 1}.")
            if config.general.verbosity > 1:
                print(e)
        stop_event.set()
        return None

    print("Which uhf goes in:", mol.uhf)

    try:
        #    ____        _   _           _
        #   / __ \      | | (_)         (_)
        #  | |  | |_ __ | |_ _ _ __ ___  _ _______
        #  | |  | | '_ \| __| | '_ ` _ \| |_  / _ \
        #  | |__| | |_) | |_| | | | | | | |/ /  __/
        #   \____/| .__/ \__|_|_| |_| |_|_/___\___|
        #         | |
        #         |_|
        optimized_molecule = iterative_optimization(
            mol=mol,
            engine=refine_engine,
            config_generate=config.generate,
            config_refine=config.refine,
            verbosity=config.general.verbosity,
        )

        print("Which uhf comes out:", mol.uhf)
    except RuntimeError as e:
        if config.general.verbosity > 0:
            print(f"Refinement failed for cycle {cycle + 1}.")
            if config.general.verbosity > 1 or config.refine.debug:
                print(e)
        return None
    finally:
        if config.refine.debug:
            stop_event.set()

[jonathan-schoeps]

Now all the requested changes should be implemented.

[marcelmbn]

LGTM.