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The permanent dipole moment of gas-phase para-amino benzoic acid revisited
KTH, Superseded Departments, Biotechnology.
KTH, Superseded Departments, Biotechnology.ORCID iD: 0000-0003-0007-0394
2004 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 121, no 1, 157-161 p.Article in journal (Refereed) Published
Abstract [en]

A study of permanent dipole moment of para-amino benzoic acid (PABA) by using various computational methods, was carried out. The dipole meoments of PABA was computed at Hartree-Fock, second-order Mφller-Plesset perturbation (MP2), coupled cluster singles and doubles (CCSD), triple corrections CCSD(T) and hybrid density functional theory at B3LYP level with different basis sets. It was found that the electron density by B3LYP resulted in large charge separation in the charge transfer molecules. It was stated that the best dipole moments were obtained at CCSD and CCSD(T) levels experiments.

Place, publisher, year, edition, pages
2004. Vol. 121, no 1, 157-161 p.
Keyword [en]
Benzene, Carrier concentration, Charge transfer, Computational geometry, Optimization, Parameter estimation, Perturbation techniques, Probability density function, Separation
National Category
Chemical Sciences
URN: urn:nbn:se:kth:diva-5081DOI: 10.1063/1.1756862ISI: 000222112100018ScopusID: 2-s2.0-3142688269OAI: diva2:7836
QC 20101004 QC 20111101. Tidigare titel: "The Permanent Dipole moment of gas phase p-aminobenzoic acid revisited".Available from: 2005-04-28 Created: 2005-04-28 Last updated: 2011-11-01Bibliographically approved
In thesis
1. Charge-transfer excitations and phtophysical properties of molecular building blocks
Open this publication in new window or tab >>Charge-transfer excitations and phtophysical properties of molecular building blocks
2005 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

This thesis reports a state-of-the-art theoretical study of photophysical properties of organic charge-transfer aromatic molecules. These molecules are building blocks of molecular functional materials used in modern photonics technology and play essential roles in chemistry and biology in general. A good understanding of these systems is thus important.

The theoretical results for permanent dipole moments of some substituted benzenes have been obtained using the coupled cluster singles and doubles (CCSD) method. The performance of density functional theory (DFT) for the geometry and electronic properties has been compared with that of traditional ab initio methods, such as Hartree-Fock, second-order Möller Plesset perturbation theory (MP2), CCSD and CCSD(T). Limitations of the DFT methods for charge transfer molecules have been demonstrated. The multi-configuration self-consistent field (MCSCF) method has been applied to understand properties of the triplet states of benzene derivatives by studying their phosphorescence with the inclusion of contributions from vibronic coupling. It has also been employed to calculate the photophysics of the thioxanthone molecule containing three benzene rings in combination with the CASPT2 method, resolving a long-standing problem concerning the possible stable conformations of the molecule.

With knowledge of the building blocks a series of porphyrin derivatives with exceptionally large two-photon absorption cross sections were designed, and proposed for use in bioimaging applications. The static and dynamic properties of a few zinc and platinum organometallic compounds, being possible candidates for optical limiting devices, have also investigated.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. 43 p.
Theses in philosophy from the Royal Institute of Technology, ISSN 1654-627X
Theoretical chemistry, Photophysical porperties, CCSD, CASSCF, Teoretisk kemi
National Category
Theoretical Chemistry
urn:nbn:se:kth:diva-184 (URN)91-7178-020-3 (ISBN)
Public defence
2005-05-12, FA32, Albanova centrum, 10:00
QC 20101011Available from: 2005-04-28 Created: 2005-04-28 Last updated: 2011-11-23Bibliographically approved

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