def move_coordinates(geo, idx1, idx2):
    """ move the atom at position idx1 to idx2, shifting all other atoms
    """

    # Get the coordinates at idx1 that are to be moved
    geo = [list(x) for x in geo]
    moving_coords = geo[idx1]

    # move the coordinates to idx2
    geo.remove(moving_coords)
    geo.insert(idx2, moving_coords)
    geo_move = tuple(tuple(x) for x in geo)
    return geo_move