Software

The following software is being co-developed:

• AKIRA - the Mode-Tracking program for the purpose-driven calculation of pre-selected molecular vibrations
  by J. Neugebauer, C. Herrmann, K. Kiewisch, S. Luber, S. Schenk and M. Reiher
  
  The standard quantum chemical calculation of vibrational spectra involves the calculation of the complete Hessian matrix, which becomes the more time-consuming the larger the molecule and/or the more elaborate the quantum chemical electronic structure method is. We have developed a conceptually new and efficient method (Mode-Tracking) for the exact calculation of only those normal modes, which are important for the physics and chemistry of the system, thus circumventing the calculation of the full Hessian matrix. Detailed studies on convergence characteristics of the Mode-Tracking principle for selectively targeting molecular properties (in particular, for calculating pre-selected molecular vibrations) have been carried out and shows the behavior of the algorithm with respect to
  
  
  • numerical accuracy and stability,
  • preconditioning,
  • choice of the guess vibration(s),
  • implicit restriction to a symmetry species,
  • near degeneracy effects,
  • intermolecular vibrations,
  • convergence to the complete spectrum as the limiting case, and
  • convergence to the lowest mode for the characterization of stationary points.
  
  Mode-Tracking is well suited in cases of very large molecules for which a complete calculation of the spectrum is not feasible, standard systems if only limited computer time is available so that a complete calculation cannot be carried out, and smaller systems in combination with highly accurate ab initio calculations.
  
  Cite this work as: M. Reiher, J. Neugebauer, J. Chem. Phys. 118 (2003), 1634-1641.
  
  Further relevant Publications:
  • M. Reiher, J. Neugebauer, Phys. Chem. Chem. Phys. 6 (2004), 4621.
  • C. Herrmann, J. Neugebauer, M. Reiher, New J. Chem. 31 (2007), 818.
  • K. Kiewisch, S. Luber, J. Neugebauer, M. Reiher, Intensity Tracking for Vibrational Spectra of Large Molecules, Chimia 63 (2009), 270-274.
  
  Currently supported program packages for calculation of primary data:
  DALTON TURBOMOLE ADF GAUSSIAN



• SNF - the program for the quantum chemical calculation of vibrational spectra
  maintained by J. Neugebauer, C. Herrmann, S. Luber, M. Reiher
  
  The program package SNF has been developed for the calculation of vibrational spectra. Infrared, Raman, and VROA spectra can be obtained using the harmonic approximation for the frequencies and the double harmonic approximation for the intensities. Vibrational frequencies are determined using numerical differentiation of analytical gradients of the total electronic energy, while infrared, Raman, and VROA intensities are obtained by numerical differentiation of dipole moments and (generalized) polarizability tensor components with respect to nuclear coordinates. SNF takes maximum advantage of the molecular point group. All required single-point calculations can be performed using coarse-grained parallelization (PVM and MPI) with automatic load-balancing.
  
  NEW FEATURES in SNF 4.0.0:
  • Improved and more user-friendly installation facilities
  • Calculation of Vibrational Raman Optical Activity (VROA) spectra
  • Direct calculation of selected IR, Raman and VROA intensities only
  • Molpro interface (for MCSCF)
  • RICC2 possible within SNF/Turbomole interface
  • Characterization of stationary points on excited-state surfaces for SNF/Turbomole interface
  • Improved interfaces to Gaussian and ADF
  • Serial version available
  • Automatic test suite available for all interfaces
  • Separate tool for plotting spectra (especially suited for VROA)
  
  Cite this work as: J. Neugebauer, M. Reiher, C. Kind, B. A. Hess, J. Comput. Chem. 23 2002, 895-910.
  
  Currently supported program packages for calculation of primary data:
  DALTON TURBOMOLE ADF MOLPRO GAUSSIAN