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First principle calculations of dipole-dipole dispersion coefficients for the ground and first pi π → π* excited states of some azabenzenes
Linköpings universitet, Institutionen för fysik, kemi och biologi, Beräkningsfysik. Linköpings universitet, Tekniska högskolan.
Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.ORCID-id: 0000-0002-6281-868X
2004 (engelsk)Inngår i: Journal of Computational Methods in Science and Engineering, ISSN 1472-7978, Vol. 4, nr 3, s. 321-332Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The complex polarization propagator method has been applied to the calculation of dipole-dipole dispersion coefficients (also known as C_6 coefficients) of pyridine, pyrazine, and s-tetrazine. These calculations refer to the electronic ground states as well as the first excited states of π → π* character. It is argued that accurate ground state dispersion coefficients are obtained with density functional theory using the B3LYP exchange-correlation functional. The proposed values for the C_6 coefficients of pyridine, pyrazine, and s-tetrazine in their ground states are 1543 a.u., 1398 a.u., and 1014 a.u., respectively. Multi-configurational complete active space calculations are performed on these compounds in their respective π → π* excited state. The isotropic averages of the frequency-dependent polarizabilities are smaller in the excited states, but the effective frequencies - defined in the London - van der Waals dispersion relation - are on the other hand larger.

sted, utgiver, år, opplag, sider
I O S Press , 2004. Vol. 4, nr 3, s. 321-332
HSV kategori
Identifikatorer
URN: urn:nbn:se:liu:diva-14049OAI: oai:DiVA.org:liu-14049DiVA, id: diva2:22527
Tilgjengelig fra: 2006-10-05 Laget: 2006-10-05 Sist oppdatert: 2018-05-24
Inngår i avhandling
1. Long-range intermolecular dispersion forces and circular dichroism spectra from first-principles calculations
Åpne denne publikasjonen i ny fane eller vindu >>Long-range intermolecular dispersion forces and circular dichroism spectra from first-principles calculations
2007 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

This work presents first-principles calculations of long-range intermolecular dispersion energies between two atoms or molecules and of electronic circular dichroism spectra of chiral molecules. The former is expressed in terms of the C6 dipole-dipole dispersion coefficients Δε, and the latter is given in terms of the extinction coefficient. In a series of publications, the complex linear polarization propagator method has been shown to be a powerful tool to provide accurate ab initio and first-principles density functional theory results. This was the case not only for the C6 dispersion coefficients but also for the electronic circular dichroism at an arbitrary wavelength ranging from the optical to the X-ray regions of the spectrum. The selected samples for the investigation of dispersion interactions in the electronic ground state are the noble gases, n-alkanes, polyacenes, azabenzenes, alkali-metal clusters, and C60. It is found that the values of C6 for the sodium-cluster-to-fullerene interactions are well within the error bars of the experiment. The proposed method can also be used to determine dispersion energies for species in their respective excited electronic states. The C6 dispersion coefficients for the first π → π* excited state of the azabenzene molecules have been obtained with the adopted method in the multiconfiguration self-consistent field approximation. The dispersion energy of the π → π* excited state is smaller than that of the ground state. It is found that the characteristic frequencies ω1 defined in the London approximation of n-alkanes vary in a narrow range which makes it possible to construct a simple structure-to-property relationship based on the number of π-bonds for the dispersion interaction in these saturated compounds. However, this simple approach is not applicable to the interactions of the π-conjugated systems since, depending on the systems, their characteristic frequencies ω1 can vary greatly. In addition, an accomplishment of calculations of the electronic circular dichroism spectra in the near-edge X-ray absorption has been demonstrated.

sted, utgiver, år, opplag, sider
Institutionen för fysik, kemi och biologi, 2007. s. 42
Serie
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1118
Emneord
van der Waals forces, dispersion forces, dispersion coefficients, polarizability, electronic circular dichroism
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-10151 (URN)978-91-85831-41-8 (ISBN)
Disputas
2007-10-02, Planck, Fysikhuset, Campus Valla, Linköping University, Linköping, 10:15 (engelsk)
Opponent
Veileder
Tilgjengelig fra: 2007-11-16 Laget: 2007-11-16 Sist oppdatert: 2013-10-02
2. First-principles calculations of long-range intermolecular dispersion forces
Åpne denne publikasjonen i ny fane eller vindu >>First-principles calculations of long-range intermolecular dispersion forces
2006 (engelsk)Licentiatavhandling, med artikler (Annet vitenskapelig)
Abstract [en]

This work presents first-principles calculations of long-range intermolecular dispersion energies between two atoms or molecules as expressed in terms of the C6 dipole-dipole dispersion coefficients. In a series of publications, it has been shown by us that the complex linear polarization propagator method provides accurate ab initio and first-principles density functional theory values of the C6 dispersion coefficients in comparison with those reported in the literature. The selected samples for the investigation of dispersion interactions in the electronic ground state are the noble gases, n-alkanes, polyacenes, azabenzenes, and C60. It has been shown that the proposed method can also be used to determine dispersion energies for species in their respective excited electronic states. The C6 dispersion coefficients for the first ππ* excited state of the azabenzene molecules have been obtained with the adopted method in the multiconfiguration self-consistent field approximation. The dispersion energy of the ππ* excited state is smaller r than that of the ground state. It is found that the characteristic frequencies ω1 defined in the London approximation of n-alkanes vary in a narrow range and that makes it possible to construct a simple structure-to-property relation based on the number of -bonds for the dispersion interaction in these saturated compounds. However, this simple approach is not applicable for the interactions of the π-conjugated systems since their characteristic frequencies ω1 vary strongly depending on the systems.

sted, utgiver, år, opplag, sider
Institutionen för fysik, kemi och biologi, 2006. s. 31
Serie
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1217
Emneord
van der Waals forces, dispersion forces, intermolecular interactions, dispersion coefficients, polarizability
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-7512 (URN)9185457892 (ISBN)
Presentation
2006-01-16, Jordan-Fermi, Fysikhuset, Campus Valla, Linköpings universitet, Linköping, 14:00 (engelsk)
Opponent
Veileder
Merknad

Report code: LIU-TEK-LIC-2006:2

Tilgjengelig fra: 2006-10-05 Laget: 2006-10-05 Sist oppdatert: 2017-12-08

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