Search for author: T. Helgaker

Found: 38 entries.

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1.

Static and frequency-dependent dipole-dipole polarizabilities of all closed-shell atoms up to radium: a four-component relativistic density functional theory study R. Bast, A. Heßelmann, P. Sałek, T. Helgaker and T. Saue Chem. Phys. Chem, 9, 445 (2009)

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2.

Electronic circular dichroism of disulphide bridge: Ab initio quantum-chemical calculations W. Skomorowski, M. Pecul, P. Sałek and T. Helgaker J. Chem. Phys. 127, 085102 (2008)

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3.

Variational and robust density fitting of four-center two-electron integrals in local metrics S. Reine, E. Tellgren, A. Krapp, T. Kjaergaard, T. Helgaker, B. Jansik, S. Høst and P. Sałek J. Chem. Phys. 129, 104101 (2008)

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4.

A linear-scaling implementation of molecular electronic self-consistent field theory. P. Sałek, S. Høst, L. Thøgersen, P. Jørgensen, P. Manninen, J. Olsen, B. Jansik, S. Reine, F. Pawlowski, T. Helgaker and S. Coriani. J. Chem. Phys 126, 114110 (2007)

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5.

A linear-scaling implementation of molecular response theory in self-consistent field electronic-structure theory S. Coriani, S. Høst, B. Jansik, L. Thøgersen, J. Olsen, P. Jørgensen, S. Reine, F. Pawlowski, T. Helgaker and P. Sałek. J. Chem. Phys. 126, 154108 (2007)

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6.

Structural and electronic properties of polyacetylene and polyyne from hybrid and Coulomb-attenuated density functionals M. J. G. Peach, E. I. Tellgren, P. Sałek, T. Helgaker and D. J. Tozer J Phys Chem B, 111, 11930 (2007)

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7.

Assessment of a Coulomb-attenuated exchange-correlation energy functional M. J. G. Peach, T. Helgaker, P. Sałek, T. W Keal, O. B. Lutnæs, D. J. Tozer and N. C Handy PCCP 2006, 8(5), 558 - 562 DOI: 10.1039/b511865d Attached: 38-camb3lyp-investigation.pdf

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8.

Benchmarking Two-Photon Absorption With CC3 Quadratic Response Theory, and Comparison With Density Functional Response Theory M. J. Paterson, O. Christiansen, F. Pawlowski, P. Jørgensen, C. Hättig, T. Helgaker and P. Sałek. J. Chem. Phys, 124, 054322 (2006)

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9.

Choice of exchange-correlation functional for computing NMR indirect spin­-spin coupling constants. T. W. Keal, T. Helgaker, P. Sałek and D. J. Tozer Chem. Phys. Lett. 425, 163-166 (2006)

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10.

Density-functional-theory study of the electric-field-induced second harmonic generation (EFISHG) of push-pull phenylpolyenes in solution L. Ferrighi, L. Frediani, C. Cappelli, P. Sałek, H. Ågren, T. Helgaker and K. Ruud Chem. Phys. Lett. 425(4-6), 267-272 (2006).

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11.

Towards black-box linear scaling optimization in Hartree-Fock and Kohn-Sham theories. S. Høst, J. Olsen, B. Jansik, P. Jørgensen, S. Reine, T. Helgaker, P. Sałek and S. Coriani Lecture Series on Computer and Computational Sciences, Vol 1. 2006. Attached: mau3.pdf

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12.

A comparison of density-functional-theory and coupled-cluster frequency-dependent polarizabilities and hyperpolarizabilities P. Sałek, T. Helgaker, O. Vahtras, H. Ågren, D. Jonsson and J. Gauss Mol. Phys. 103 (2-3) 439-450 (2005)

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13.

Calculations of two-photon charge-transfer excitations using Coulomb-attenuated density-functional theory E. Rudberg, P. Sałek, T. Helgaker and H. Ågren J. Chem. Phys. 123, 184108 (2005)

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14.

Density-functional theory study of electric and magnetic properties of hexafluorobenzene in the vapor phase A. Rizzo, C. Cappelli, B. Jansik, D. Jonsson, P. Sałek, S. Coriani, D. J. D. Wilson, T. Helgaker and H. Ågren J. Chem. Phys, 122, 234314 (2005)

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15.

Linear response at the 4-component relativistic density-functional level: application to the frequency-dependent dipole moment polarizability of Hg, AuH and PtH. P. Sałek, T. Helgaker and T. Saue Chem. Phys., 311(1) 187-201 (2005)

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16.

The trust-region self-consistent field method in Kohn-­Sham density-functional theory L. Thøgersen, J. Olsen, A. Köhn, P. Jørgensen, P. Sałek and T. Helgaker J. Chem. Phys. 123, 074103 (2005)

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17.

Linear-scaling formation of Kohn-Sham Hamiltonian: Application to the calculation of excitation energies and polarizabilities of large molecular systems M. Watson, P. Sałek, P. Macak and T. Helgaker J. Chem. Phys., 121, 2915 (2004)

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18.

The calculation of indirect nuclear spin--spin coupling constants in large molecules. M. A. Watson, P. Sałek, P. Macak, M. Jaszu\'nski and T. Helgaker Chemistry - A European Journal, 10, 4627 (2004)

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19.

The trust-region self-consistent field method: Towards a black-box optimization in Hartree--Fock and Kohn--Sham theories. L. Thøgersen, J. Olsen, D. Yeager, P. Jørgensen and P. Sałek and T. Helgaker J. of Chem. Phys. 121, 16 (2004)

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20.

Calculations of two-photon absorption cross sections by means of density functional theory P. Sałek, O. Vahtras, J.-D. Guo, Y. Luo, T. Helgaker and H. Ågren Chem. Phys. Lett., 374 (2003) 446.

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21.

Density functional theory of nonlinear triplet response properties with applications to phosphorescence I. Tunell, Z. Rinkevicius, O. Vahtras, P. Sałek, T. Helgaker and H. Ågren J. Chem. Phys. 119, 11024 (2003)

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22.

Sternheimer shieldings and EFG polarizabilities: a Density Functional Theory study A. Rizzo, K. Ruud, T. Helgaker, P. Sałek, H. Ågren and O.Vahtras Chem. Phys. Lett. 372, 377 (2003)

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23.

Density-functional theory of linear and nonlinear time-dependent molecular properties P. Sałek, O. Vahtras, T. Helgaker and H. Ågren J. Chem. Phys. 117, 9630 (2002).

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24.

Generalized integral-screening for efficient calculations of nonlinear optical properties of large molecules K, Ruud, D. Jonsson, P. Norman, H. Ågren, T. Saue, H.J.Aa. Jensen, P. Dahle and T. Helgaker J. Chem. Phys. 108, 7973 (1998)

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25.

The Cotton-Mouton effect of liquid water. Part II: The semi-continuum model. K. Ruud, H. Ågren, P. Dahle, T. Helgaker, A. Rizzo, S. Coriani, H. Koch, K. Sylvester-Hvid and K.V. Mikkelsen J.Chem.Phys. \bf 108, 599 (1998)

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26.

The electric and magnetic properties of fullerenes D. Jonsson, P. Norman, K. Ruud, H. Ågren and T. Helgaker J. Chem. Phys. \bf 109, 572 (1998)

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27.

The Hartree-Fock limit magnetizability of C60 K. Ruud, H. Ågren, T. Helgaker, P. Dahle, H. Koch and P.R. Taylor Chem. Phys. Lett. \bf 285, 205 (1998)

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28.

Efficient parallel implementation of response theory: Calculations of the second hyperpolarizabilities of polyacenes P. Norman, D. Jonsson, H. Ågren, P. Dahle, K. Ruud, T. Helgaker and H. Koch Chem. Phys. Letters \bf 253, 1 (1996)

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29.

Random-phase calculations of frequency dependent polarizabilities and hyperpolarizabilities of long polyene chains Y. Luo, H. Ågren, H. Koch, P. Jørgensen and T. Helgaker Phys. Rev. B \bf 51, 14949 (1995)

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30.

The Vegard-Kaplan band and the phosphorescent decay of N2. J. Olsen, B.F. Minaev, O. Vahtras, H. Ågren, P. Jørgensen, H.J. Aa. Jensen and T. Helgaker Chem. Phys. Letters 231, 387 (1995).

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31.

Ab initio study of the NMR shielding constants and spin-spin coupling constants in cyclopropene. Andrzej Barszczewicz, Michal Jaszunski, Krystyna Kamielnska-Trela, T. Helgaker, Poul Jørgensen and O. Vahtras Theo. Chim. Acta 87, 19 (1993)

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32.

Direct atomic-orbital-based self-consistent-field calculations of non-linear molecular properties. Application to frequency dependent hyperpolarizabilities of para-nitroanaline H. Ågren, O. Vahtras, H. Koch, T. Helgaker and P. Jørgensen J. Chem. Phys. \bf 98, 6417 (1993)

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33.

Large scale random phase calculations for direct self-consistent field wave functions H. Koch, H. Ågren, T. Helgaker, P. Jørgensen and H.J. Aa. Jensen Chem. Phys. \bf 172, 13 (1993)

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34.

The nuclear spin-spin coupling in N2 and CO. O. Vahtras, H. Ågren, Poul Jørgensen, T. Helgaker and H. Jörgen Aa. Jensen Chem. Phys. Lett. \bf 209, 201 (1993)

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35.

Indirect nuclear spin-spin coupling constants from multiconfiguration linear response theory O. Vahtras, H. Ågren, Poul Jørgensen, H. Jørgen Aa. Jensen, Søren Padkjær and T. Helgaker J. Chem. Phys. 96, 6120 (1992)

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36.

Multiconfigurational quadratic response functions for singlet and triplet perturbations: The phosphorescence lifetime of formaldehyde. O. Vahtras, H. Ågren, Poul Jørgensen, H. Jorgen Aa. Jensen, T. Helgaker and J. Olsen J. Chem. Phys. 97, 9178 (1992)

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37.

Spin-orbit coupling constants in a multiconfiguration linear response approach O. Vahtras, H. Ågren, P. Jørgensen, H. J. Aa. Jensen, T. Helgaker and J. Olsen J. Chem. Phys. 96, 2118 (1992)

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38.

The second-order energy contribution from the spin-orbit interaction operator to the potential energy curve of Cr2 O. Vahtras, H. Ågren, P. Jørgensen, H. J. Aa. Jensen and T. Helgaker Int. J. Quant. Chem. 41, 729 (1992)

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