FRAGMENT: A Collection of Scripts to Obtain Magnetic Exchange, Electron Transfer and Orbital Energy on Polyoxometalates

A new computer program called FRAGMENT has been designed to help MOLCAS users in the task of preparing the input files for spectroscopic calculations on embedded fragments of magnetic molecules. FRAGMENT is built as a collection of bash shell scripts (FRAGMENTador and FRAGMENTazor) and can execute the following operations: (a) read atomic coordinate files of complex molecules and largely automate the preparation of a large variety of molecular fragments; (b) perform Bond Valence Sum calculations, (c) prepare POV-Ray files for raytracing representations of said fragments and (d) extract all in-fragment angles and distances of possible magnetostructural meaning; (e) manage different programs (seward, scf, rasscf) of the MOLCAS chain, including (f) preparing the input for the seward program, (g) checking the convergence of scf and rasscf programs, (h) automatically preparing inputs with different spin multiplicity for calculating magnetic exchange, electron transfer and orbital energy differences and (i) calculate said parameters from the results. FRAGMENT has already been applied for the investigation of a mixed-valence polyoxometalate with interest in molecular magnetism and quantum computing.