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- Publications
- Influence
The Method of Second Quantization
- J. Olsen
- Mathematics
- 1992
In the usual formalism of quantum mechanics, the first quantization formalism, observables are represented by operators and the wave functions are normal functions. In the method of second… Expand
Determinant based configuration interaction algorithms for complete and restricted configuration interaction spaces
A restricted active space (RAS) wave function is introduced, which encompasses many commonly used restricted CI expansions. A highly vectorized algorithm is developed for full CI and other RAS… Expand
Molecular Electronic-Structure Theory: Helgaker/Molecular Electronic-Structure Theory
- Trygve Helgaker, P. Jørgensen, J. Olsen
- Physics
- 11 August 2000
Transonic Flutter Analysis of a Rectangular Wing with Conventional Airfoil Sections
Flutter analysts have encountered considerable analytical difficulties in the prediction of the flutter stability of aircraft operating in the transonic Mach number regime. Because of the shocks and… Expand
Solution of the large matrix equations which occur in response theory
- J. Olsen, H. Jørgen, A. Jensen, P. Jørgensen
- Mathematics
- 1 February 1988
Abstract The eigenvalue equation and the sets of linear equations that occur in linear and nonlinear response function calculations have a specific paired structure. We have developed iterative… Expand
The trust-region self-consistent field method: towards a black-box optimization in Hartree-Fock and Kohn-Sham theories.
- Lea Thøgersen, J. Olsen, D. Yeager, P. Jørgensen, P. Sałek, T. Helgaker
- Medicine, Chemistry
- The Journal of chemical physics
- 18 June 2004
The trust-region self-consistent field (TRSCF) method is presented for optimizing the total energy E(SCF) of Hartree-Fock theory and Kohn-Sham density-functional theory. In the TRSCF method, both the… Expand
Linear-scaling symmetric square-root decomposition of the overlap matrix.
- B. Jansik, S. Høst, P. Jørgensen, J. Olsen, T. Helgaker
- Mathematics, Medicine
- The Journal of chemical physics
- 23 March 2007
We present a robust linear-scaling algorithm to compute the symmetric square-root or Lowdin decomposition of the atomic-orbital overlap matrix. The method is based on Newton-Schulz iterations with a… Expand
Computational methods for studies of multiexciton complexes
- T. Vänskä, M. Lindberg, J. Olsen, D. Sundholm
- Physics
- 1 December 2006
Powerful computational methods are presented for studies of energy levels, photon-recombination rates, and phonon-relaxation rates of neutral and charged multiexciton complexes at correlated levels… Expand
Linear and nonlinear response functions for an exact state and for an MCSCF state
We have examined the response of an exact and an MCSCF reference state to a general time‐dependent field. The time development of both the exact and the MCSCF reference state have been parametrized… Expand
Accuracy of atomization energies and reaction enthalpies in standard and extrapolated electronic wave function/basis set calculations
- Keld L. Bak, P. Jørgensen, J. Olsen, T. Helgaker, W. Klopper
- Chemistry
- 17 May 2000
The accuracy of standard ab initio wave-function calculations of atomization energies and reaction enthalpies has been assessed by comparing with experimental data for 16 small closed-shell molecules… Expand