1,721,084 research outputs found
Ricci (Matteo) The True Meaning of the Lord of Heaven (T'ien-chu Shih-i)
No full textAubin Françoise. Ricci (Matteo) The True Meaning of the Lord of Heaven (T'ien-chu Shih-i). In: Archives de sciences sociales des religions, n°64/2, 1987. pp. 321-323
Van der Waals effects with Density Functional Theory: exact approach for small isolated systems and improved description of interlayer bonding in TiS2.
Full text linkIn this Thesis we propose to improve the description of vdW effects with DFT considering
two approaches. In the first one we derive a novel sum-rule approach,
applied to simple, but emblematic, systems such as the Hydrogen atom, a system of
quantum harmonic oscillators and a particle confined in a spherical well potential. In
this context, firstly, we derive exact expressions concerning both polarizability and
vdW density functionals, giving anlytical results when it is possible and then we make
a comparison between our results and those obtained within popular, well established
theoretical vdW approaches.
In the second part of the Thesis instead we mainly focus on a the description of vdW
interactions with DFT considering the specific class of layered materials, analyzing one
of them, TiS2, in detail. We characterize the way vdW interactions are modeled by
state of the art Density Functional Theory (DFT) methods, particularly focusing on the
electron density distribution, being this latter the physical quantity lying at the core
of DFT. We provide extensive benchmarking for the electron density distribution, first
by reproducing reported hortcomings of standard approaches, and, then, on the basis
of physical considerations, by generating a novel pseudopotential whose integration in
a DFT scheme almost totally overcome the issues mentioned above.In this Thesis we propose to improve the description of vdW effects with DFT considering
two approaches. In the first one we derive a novel sum-rule approach,
applied to simple, but emblematic, systems such as the Hydrogen atom, a system of
quantum harmonic oscillators and a particle confined in a spherical well potential. In
this context, firstly, we derive exact expressions concerning both polarizability and
vdW density functionals, giving anlytical results when it is possible and then we make
a comparison between our results and those obtained within popular, well established
theoretical vdW approaches.
In the second part of the Thesis instead we mainly focus on a the description of vdW
interactions with DFT considering the specific class of layered materials, analyzing one
of them, TiS2, in detail. We characterize the way vdW interactions are modeled by
state of the art Density Functional Theory (DFT) methods, particularly focusing on the
electron density distribution, being this latter the physical quantity lying at the core
of DFT. We provide extensive benchmarking for the electron density distribution, first
by reproducing reported hortcomings of standard approaches, and, then, on the basis
of physical considerations, by generating a novel pseudopotential whose integration in
a DFT scheme almost totally overcome the issues mentioned above
Ferroelectric and structured phases from polar tapered mesogens
No full textWe investigate the effect of changing the molecular dipole strength on the liquid crystal phases formed in a system of tapered Gay-Berne particles with an axial dipole. We show that increasing the strength of the dipole has a profound effect on the stability and molecular organisation of the phases and eventually destroys the polar ferroelectric nematic
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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