Physics / Fizik

Permanent URI for this collectionhttps://hdl.handle.net/11147/6

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Scopus Q: search.filters.scopusQuartile.Q3Subject: search.filters.subject.Monte Carlo method

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  • Article
    Citation - WoS: 2
    Citation - Scopus: 2
    Electronic Structure and Correlations of Vitamin B12 Studied Within the Haldane-Anderson Impurity Model
    (Springer Verlag, 2016) Kandemir, Zafer; Mayda, Selma; Bulut, Nejat
    We study the electronic structure and correlations of vitamin B12 (cyanocobalamine) by using theframework of the multi-orbital single-impurity Haldane-Anderson model of atransition-metal impurity in a semiconductor host. The parameters of the effectiveHaldane-Anderson model are obtained within the Hartree-Fock (HF) approximation. Thequantum Monte Carlo (QMC) technique is then used to calculate the one-electron andmagnetic correlation functions of this effective model. We observe that new states forminside the semiconductor gap found by HF due to the intra-orbital Coulomb interaction atthe impurity 3d orbitals. In particular, the lowest unoccupiedstates correspond to an impurity bound state, which consists of states from mainly the CNaxial ligand and the corrin ring as well as the Co eg-like orbitals. We alsoobserve that the Co (3d) orbitals can develop antiferromagneticcorrelations with the surrounding atoms depending on the filling of the impurity boundstates. In addition, we make comparisons of the HF+QMC data with the density functionaltheory calculations. We also discuss the photoabsorption spectrum of cyanocobalamine.
  • Article
    Citation - WoS: 35
    Citation - Scopus: 53
    Alignment of the Cms Muon System With Cosmic-Ray and Beam-Halo Muons
    (IOP Publishing Ltd., 2010) Demir, Durmuş Ali; Karapınar, Güler
    The CMS muon system has been aligned using cosmic-ray muons collected in 2008 and beam-halo muons from the 2008 LHC circulating beam tests. After alignment, the resolution of the most sensitive coordinate is 80 microns for the relative positions of superlayers in the same barrel chamber and 270 microns for the relative positions of endcap chambers in the same ring structure. The resolution on the position of the central barrel chambers relative to the tracker is comprised between two extreme estimates, 200 and 700 microns, provided by two complementary studies. With minor modifications, the alignment procedures can be applied using muons from LHC collisions, leading to additional significant improvements.