Fen Edebiyat Fakültesi / Faculty of Letters and Sciences
https://hdl.handle.net/11413/10
Fen Edebiyat Fakültesi bağlı programlar bu bölüm altında listelenir.2018-02-23T20:22:46ZMatrix Isolation Infrared Spectra and Photochemistry of Hydantoin
https://hdl.handle.net/11413/1829
Matrix Isolation Infrared Spectra and Photochemistry of Hydantoin
Öğrüç Ildız, Gülce; Nunes, Claudio M.; Fausto, Rui
Hydantoin (C3H4N2O2, 2,4-imidazolidinedione) was isolated in argon matrix at 10 K and its infrared spectrum and unimolecular photochemistry were investigated. The molecular structure of the compound was studied both at the DFT(B3LYP) and MP2 levels of approximation with valence triple- and quadruple-zeta basis sets (6-311++G(d,p); cc-pVQZ). It was concluded that the minima in the potential energy surfaces of the molecule correspond to C-1 symmetry structures. However, the energy barrier separating the two-equivalent-by-symmetry minima stays below their zero-point energy, which makes the C-s symmetry structure, which separates the two minima, the experimentally relevant one. The electronic structure of the molecule was studied in detail by performing the Natural Bond Orbital analysis of its electronic configuration within the DFT(B3LYP)/cc-pVQZ space. The infrared spectrum of the matrix isolated compound was fully assigned also with help of the theoretically predicted spectrum. Upon irradiation at lambda = 230 nm, matrix-isolated hydantoin was found to photofragment into isocyanic acid, CO, and methylenimine.
2013-01-31T00:00:00ZBounded Log-Harmonic Functions with Positive Real Part
https://hdl.handle.net/11413/1827
Bounded Log-Harmonic Functions with Positive Real Part
Özkan Uçar, Hatice Esra; Polatoğlu, Yaşar
Let H(D) be the linear space of all analytic functions defined on the open unit disc D = {z vertical bar vertical bar z vertical bar < 1}, and let B be the set of all functions w(z) is an element of H(D) such that vertical bar w(z)vertical bar < 1 for all z is an element of D. A log-harmonic mapping is a solution of the non-linear elliptic partial differential equation (f) over bar ((z) over bar) = w(z) ((f) over bar /f) f(z), where w(z) is the second dilatation off and w(z) is an element of B. In the present paper we investigate the set of all log-harmonic mappings R defined on the unit disc D which are of the form R = H(z)<(G(z))over bar>, where H(z) and G(z) are in H(D), H(0) = G(0) = 1, and Re(R) > 0 for all z is an element of D. The class of such functions is denoted by P-LH. (C) 2012 Elsevier Inc. All rights reserved.
2013-03-01T00:00:00ZModeling Solar Cycles 15 to 21 Using a Flux Transport Dynamo
https://hdl.handle.net/11413/1817
Modeling Solar Cycles 15 to 21 Using a Flux Transport Dynamo
Işık, Emre; Jiang, J.; Cameron, R. H.; Schmitt, D.
Context. The Sun's polar fields and open flux around the time of activity minima have been considered to be strongly correlated with the strength of the subsequent maximum of solar activity.
Aims. We aim to investigate the behavior of a Babcock-Leighton dynamo with a source poloidal term that is based on the observed sunspot areas and tilts. In particular, we investigate whether the toroidal fields at the base of convection zone from the model are correlated with the observed solar cycle activity maxima.
Methods. We used a flux transport dynamo model that includes convective pumping and a poloidal source term based on the historical record of sunspot group areas, locations, and tilt angles to simulate solar cycles 15 to 21.
Results. We find that the polar fields near minima and the toroidal flux at the base of the convection zone are both highly correlated with the subsequent maxima of solar activity levels (r = 0.85 and r = 0.93, respectively). Conclusions. The Babcock-Leighton dynamo is consistent with the observationally inferred correlations.
2013-05-01T00:00:00ZNew Ring-Like Models and ab Initio DFT Study of the Medium-Range Structures, Energy and Electronic Properties of GeSe2 Glass
https://hdl.handle.net/11413/1801
New Ring-Like Models and ab Initio DFT Study of the Medium-Range Structures, Energy and Electronic Properties of GeSe2 Glass
Akalın, Elif; Akyüz, Sevim; Holomb, R.; Mitsa, V.
Ab initio DFT calculations were performed on GenSem nanoclusters (n=2, 3, 5, 6, 12; m=6-9, 14, 16, 30) that represent the local structure of GeSe2 glass and on some defect' GenSem clusters that are thought to be related to the inhomogeneity of the structure at the nanoscale. The optimal geometries, total energies and their derivatives as well as the electronic properties of GenSem nanoclusters were calculated using traditional DFT method. In addition, the TD-DFT method has been applied to calculate the electronic band gaps of the clusters. The calculated physico-chemical properties of GenSem nanoclusters and their couplings with the local-and medium-range order structure formations in GeSe2 glass are analysed and discussed.
2013-07-01T00:00:00Z