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- Cappelli, Chiara, et al.
(författare)
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The molecular electric quadrupole moment and electric field gradient induced birefringence (Buckingham effect) of Cl2
- 2004
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Ingår i: Journal of Computational Methods in Sciences and Engineering. - 1472-7978 .- 1875-8983. ; 4:3, s. 365-380
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Tidskriftsartikel (refereegranskat)abstract
- An ab initio investigation of the molecular properties rationalizing the electric-field-gradient induced birefringence (Buckingham effect) for Cl_2 is presented. The quadrupole moment is determined using hierarchies of basis sets and wavefunction models. The electric dipole polarizability, the dipole - dipole - quadrupole and dipole - dipole - magnetic dipole hyperpolarizabilities are determined exploiting a Coupled Cluster Singles and Doubles (CCSD) response approach. The properties are zero-point vibrationally averaged, and the contribution of excited ro-vibrational states accounted for. To this end, the interatomic ^1Σ_g^+ ground state potential has been computed at CCSD plus perturbative triples - CCSD(T) - level employing a large augmented correlation consistent basis set. The effect of relativity is estimated at the Dirac-Hartree-Fock level. Our best value for the quadrupole moment of Cl_2 is (2.327 ± 0.010) au and it is in excellent agreement with experiment which, after revision and dependent on the procedure employed for correcting the original estimate of (2.24 ± 0.04) au of Graham et al., [Mol. Phys., 93, 49, (1998)], ranges from (2.31 ± 0.04) au to (2.36 ± 0.04) au.
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| 2. |
- Tavanti, Monica, 1972-
(författare)
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On the Relative Utility of 3D Interfaces
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Three-dimensional (3D) interfaces are made with the ambition to reinvent traditional two-dimensional (2D) displays into intuitive 3D environments that allow natural interactions and guarantee users’ satisfaction. However, reality is far from the expectations and 3D interfaces remain experimental. The results of empirical studies comparing 2D and 3D interfaces are incoherent and do not indisputably endorse the development of 3D applications. The reason behind this incoherency is that empirical comparisons often discard several factors that go beyond the specific style of the interface itself although they play a major role in human performance. Specifically: perceptual factors, factors related to semantics, contextual factors.The identification of these factors was carried out through a set of empirical studies tackling two applications domains: information management (namely, the retrieval of data and on spatial memory tasks) and Air Traffic Control. Concerning the first domain, the results suggest that 3D interfaces can support spatial memory if the 3D interface is provided with a spatial structure that has also a semantic function. Also, the specific content of the objects disseminated in the 3D structure seem to affect performance. It is argued that when there is a strategic coupling of the semantics of the spatial structure with the meanings of the objects, 3D interfaces could enhance spatial memory. Concerning the second domain, the results indicate that 3D interfaces could support controllers’ tasks only for a limited set of activities. These do not include standard monitoring tasks where the presence of 3D would actually cause detriment to the performance due to perceptual biases. Finally, it is claimed that the idea of familiarity with an interface style can affect the way people interact with it and, despite the fuzziness of the concept, familiarity may represent a real challenge in users’ acceptance of 3D interfaces.
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