| Autor: |
Jørgensen P; Department of Chemistry, University of Aarhus, Langelandsgade 140, DK-8000 Aarhus C, Denmark., Olsen J; Department of Chemistry, University of Aarhus, Langelandsgade 140, DK-8000 Aarhus C, Denmark., Johansen MB; Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark., von Buchwald TJ; Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark.; DTU Chemistry, Technical University of Denmark, Kemitorvet Bldg. 260, DK-2800 Kgs. Lyngby, Denmark., Hillers-Bendtsen AE; Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark., Mikkelsen KV; Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark., Helgaker T; Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry, University of Oslo, P. O. Box 1033, Blindern, N-0315 Oslo, Norway. |
| Abstrakt: |
Conventional quantum-mechanical calculations of molecular properties, such as dipole moments and electronic excitation energies, give errors that depend linearly on the error in the wave function. An exception is the electronic energy, whose error depends quadratically on the error in wave function. We here describe how all properties may be calculated with a quadratic error, by setting up a variational Lagrangian for the property of interest. Because the construction of the Lagrangian is less expensive than the calculation of the wave function, this approach substantially improves the accuracy of quantum-chemical calculations without increasing cost. As illustrated for excitation energies, this approach enables the accurate calculation of molecular properties for larger systems, with a short time-to-solution and in a manner well suited for modern computer architectures. |
