DKH in Molcas

• external page MOLCAS version 7 (arbitrary-order DKH Hamiltonian and property modules)

MOLCAS is a powerful program package, which was designed for ab initio electronic structure calculations on arbitrary molecules covering the whole periodic table including compounds of heavy transition elements, lanthanides and actinides.

1. Picture-change-corrected electric field like properties with analytic arbitrary-order DKH-transformations  (with R. Lindh, Lund, and G. Barone, Palermo)
   
   • A rapid convergence of the DKH property expansion towards the four-component Dirac-Hartree-Fock reference was found. Our results demonstrate that in closed-shell cases the scalar-relativistic DKH(2,2) approach which is of second order in the external potential for both orbitals and property operator yields a remarkable accuracy. As a high-order DKH model, which is independent of the parametrization of the unitary matrices and valid for the whole periodic table, we recommend DKH(4,3).
2. Determination of  ¹¹⁹Sn Mössbauer parameters  (with R. Lindh, Lund, and G. Barone, Palermo)
   
   • The application of our arbitrary order DKH property transformation was recently extended to the field of theoretical Mössbauer spectroscopy. An analytic picture-change-corrected DKH approach in combination with density functional theory proved to yield a reliable nuclear quadruple moment of ¹¹⁹Sn and nuclear quadrupole splitting parameters for a variety of tin compounds.
3. Development of local DKH scheme for relativistic linear scaling calculations on large molecules (with R. Lindh, Lund)
   • Current developments in MOLCAS aim at a local DKH scheme for scalar-relativistic calculations on large molecules. Our concept is to include only these atoms of a particular molecule in the DKH transformation, for which a relativistic treatment is mandatory. This approach allows for linear scaling of the DKH transformation with the molecule size.
4. Mössbauer ⁵⁷Fe isomer shift in arbitrary iron compounds (with R. Lindh, Lund, and G. Barone, Palermo)
   
   • The ⁵⁷Fe isomer shift is a Mössbauer parameter that is strongly affected by the valence and spin state of a specific iron species. In a current study we investigate the ⁵⁷Fe isomer shift in various iron compounds applying density functional theory and our scalar-relativistic picture-change-corrected DKH approach.

external page The Reiher group is part of the MOLCAS network.

Joined publications with the Lund-Group

R. Mastalerz, G. Barone, R. Lindh, M. Reiher, external page Analytic high-order Douglas-Kroll-Hess Electric Field Gradients,  J. Chem. Phys. 127, 2007, 074105.

G. Barone, R. Mastalerz, M. Reiher, R.Lindh, external page Nuclear Quadrupole Moment of 119Sn, J. Phys. Chem. A 112 2008 1666-1672.