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Efficient calculation of ROA tensors with analytical gradients and fragmentation

  • Thorvaldsen, Andreas J. Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Tromsø, Norway
  • Gao, Bin Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Tromsø, Norway
  • Ruud, Kenneth Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Tromsø, Norway
  • Fedorovsky, Maxim Department of Chemistry, University of Fribourg, Switzerland
  • Zuber, Gérard Department of Chemistry, University of Fribourg, Switzerland
  • Hug, Werner Department of Chemistry, University of Fribourg, Switzerland
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    24.09.2012
Published in:
  • Chirality. - 2012, vol. 24, no. 12, p. 1018–1030
raman optical activity
theoretical calculations
analytic methods
basis sets
English We present the results of calculations of Raman optical activity spectra of sizable systems from optical tensors of the fragments, the tensors calculated by an analytic approach at the time-dependent Hartree–Fock level of theory. The analytic approach permits large basis sets which, together with the limited geometrical extent of the fragments, obviates the need for the use of London-type orbitals. The implementation of the analytical gradient approach is formulated in the atomic orbital basis by using the elements of the density matrix as variational parameters. This makes the approach directly applicable to linear scaling methods. We do not solve the response equations for the geometrical distortions of the nuclei but determine instead the second-order perturbed densities with respect to the electromagnetic field perturbations. The number of perturbed density matrices that needs to be determined is thus independent of the number of nuclei, making the approach applicable to fragments with many nuclei and with good quality basis sets. Compared to numerical differentiation schemes, the analytical approach is about 10 times faster even for moderately sized molecules.
Faculty
Faculté des sciences et de médecine
Department
Département de Chimie
Language
  • English
Classification
Chemistry
License
License undefined
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Persistent URL
https://folia.unifr.ch/unifr/documents/302771
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