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Ab-Initio calculations of the CO adsorption and dissociation on substitutional Fe-Cu surface alloys relevant to Fischer-Tropsch Synthesis: Bcc-(Cu)Fe(100) and fcc-(Fe)Cu(100)
, Article Surface and Interface Analysis ; Volume 45, Issue 7 , 2013 , Pages 1081-1087 ; 01422421 (ISSN) ; Fazeli, E ; Joshani, A ; Gholami, M ; Sharif University of Technology
Abstract
Direct CO dissociation is seen the main path of the first step in the Fischer-Tropsch Synthesis (FTS) on the reactive iron surfaces. Cu/Fe alloy film is addressed with various applications over face-centered-cubic (fcc)-Cu and body-centered-cubic (bcc)-Fe in the FTS, i.e. preventing iron carbide formation (through direct CO dissociation) by moderating the surface reactivity and facilitating the reduction of iron surfaces, respectively. In this study by density functional theory, the stable configurations of CO molecule on various Cu/Fe alloys over fcc-Cu(100) and bcc-Fe(100) surfaces with different CO coverage (25% and 50%) have been evaluated. Our results showed that the ensemble effect...
Classification of the nonlinear dynamics in an initially curved bistable micro/nanoelectro-mechanical system resonator
, Article Micro and Nano Letters ; Volume 10, Issue 10 , Oct , 2015 , Pages 583-588 ; 17500443 (ISSN) ; Hairi Yazdi, M. R ; Nejat Pishkenari, H ; Maani Miandoab, E ; Ouakad, H.M ; Sharif University of Technology
Institution of Engineering and Technology
2015
Abstract
The nonlinear dynamics of a bistable micro/nano-electro-mechanical system resonator composed of an arch-shaped microbeam is investigated. The initially curved microbeam is actuated through a combined DC and AC electrostatic parallel plate field. A single degree of freedom model obtained using the Galerkin's decomposition method with distributed electrostatic force is implemented in order to investigate the resonator dynamics near its primary resonance. According to the shape of the potential energy function which depends on the system parameters, the nonlinear dynamics of the system are classified into certain categories. The appearance of various nonlinear phenomena including dynamic...
Ionic liquid based on α-amino acid anion and N7,N9-dimethylguaninium cation ([dMG][AA]): Theoretical study on the structure and electronic properties
, Article Journal of Physical Chemistry A ; Volume 116, Issue 22 , April , 2012 , Pages 5436-5444 ; 10895639 (ISSN) ; Fattahi, A ; Bayat, A ; Sharif University of Technology
2012
Abstract
The interactions between five amino acid based anions ([AA] - (AA = Gly, Phe, His, Try, and Tyr)) and N7,N9-dimethylguaninium cation ([dMG] +) have been investigated by the hybrid density functional theory method B3LYP together with the basis set 6-311++G(d,p). The calculated interaction energy was found to decrease in magnitude with increasing side-chain length in the amino acid anion. The interaction between the [dMG] + cation and [AA] - anion in the most stable configurations of ion pairs is a hydrogen bonding interaction. These hydrogen bonds (H bonds) were analyzed by the quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analysis. Finally, several correlations...