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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

299 22

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

681 8

Molecular Electronic-Structure Theory: Helgaker/Molecular Electronic-Structure Theory

- Trygve Helgaker, P. Jørgensen, J. Olsen
- Physics
- 11 August 2000

1,155 4

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

56 4

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

156 3

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

61 3- PDF

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

44 3

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

13 3

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

825 2- PDF

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

190 2