qcmr.moldenformat

Read and write Molden Format.

Note: This package provides an interface for files in molden format, but is not affiliated in any way with Molden program or its Author.

Note: This package is based on the code adapted from package natorbs, Copyright 2021 Jagiellonian University, Dr hab. Mariusz Radoń; adapted and modified by Mariusz Radoń, 2026. See NOTICE.txt. The code derived from natorbs is BSD-3-Clause; newly written code is MIT.

Usage

• Reading Molden Format:

  from qcmr.moldenformat import read_moldenformat
  mf = read_moldenformat('h2o.molden')
  print(mf.atoms)
  print(mf.moenergies)
  

  Above, mf returned by read_moldenformat()is an instance of class MoldenFormat. It always containing attributes: atoms and length_unit. It may contain other attributes, in particular gbasis (GTO basis set) or sbasis (STO basis set) as well as moenergies, mooccups, mosyms and mocoeffs related to molecular orbitals. These are defined analogously as data parsed by cclib. The history of geometry optimization is stored in attribute geometries. Anything not parsed by current implementation is stored as ASCII text in attribute extensions.

• Writing Molden Format

  from qcmr.moldenformat import write_moldenformat
  write_moldenformat(data, 'h2o.molden')
  

  Above, data could be either a genuine object of class MoldenFormat (returned by read_moldenformat(), see above) or any object containing identically named attributes, from which a valid MoldenFormat object could be constructed. It may also be a dictionary containing the relevant attributes as keys. Example of such usage:

  data = {
      'atoms': [
          ('O', [0.000000,     0.000000,     0.114879]),
          ('H', [0.000000,     0.750347,    -0.459515]),
          ('H', [0.000000,    -0.750347,    -0.459515]),
      ],
      'length_unit': 'Angstrom'
  }
  write_moldenformat(data, 'h2o.molden')