Modeling the Active Sites in Metalloenzymes. 3. Density Functional Calculations on Models for [Fe]-Hydrogenase:  Structures and Vibrational Frequencies of the Observed Redox Forms and the Reaction Mechanism at the Diiron Active Center

2001 ◽  
Vol 123 (16) ◽  
pp. 3734-3742 ◽  
Author(s):  
Zexing Cao ◽  
Michael B. Hall
Keyword(s):  
Reaction Mechanism ◽  
Active Center ◽  
Density Functional Calculations ◽  
Active Sites ◽  
Density Functional ◽  
Vibrational Frequencies ◽  
Redox Forms

Density Functional Theory Study of Thiophene Desulfurization and Conversion of Desulfurization Product on Ni(111) Surface and Ni55 Cluster: Implication for the Mechanism of Reactive Adsorption Desulfurization over Ni/ZnO Catalysts

2021 ◽  
Author(s):  
Houyu Zhu ◽  
Xin Li ◽  
Naiyou Shi ◽  
Xuefei Ding ◽  
Zehua Yu ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Reaction Mechanism ◽  
Active Center ◽  
Density Functional ◽  
Density Functional Theory Study ◽  
Functional Theory ◽  
Reactive Adsorption ◽  
Adsorption Desulfurization

Ni/ZnO catalysts have been well recognized by industry and academia for exhibiting excellent desulfurization activities. However, intrinsic reaction mechanism on Ni active center is still obscure. Herein, we performed periodic...

The structure and activity of potassium supported on SBA-15 molecular sieve: Density functional theory study

2014 ◽  
Vol 13 (01) ◽  
pp. 1350076 ◽  
Author(s):  
Bing Liu ◽  
Daxi Wang ◽  
Zhongxue Wang ◽  
Zhen Zhao ◽  
Yu Chen ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Lewis Acid ◽  
Molecular Sieve ◽  
Active Sites ◽  
Density Functional ◽  
Structural Model ◽  
Vibrational Frequencies ◽  
Oxygen Molecule ◽  
Lewis Base ◽  
Functional Theory

The geometries, vibrational frequencies, electronic properties and reactivity of potassium supported on SBA-15 have been theoretically investigated by the density functional theory (DFT) method. The structural model of the potassium supported on SBA-15 was constructed based on our previous work [Wang ZX, Wang DX, Zhao Z, Chen Y, Lan J, A DFT study of the structural units in SBA-15 mesoporous molecular sieve, Comput. Theor. Chem.963, 403, 2011]. This paper is the extension of our previous work. The most favored location of potassium atom was obtained by the calculation of substitution energy. The calculated vibrational frequencies of K /SBA-15 are in good agreement with the experimental results. By analyzing the properties of electronic structure, we found that the O atom of Si - O (2)- K group acts as the Lewis base center and the K atom acts as the Lewis acid center. The reactivity of K /SBA-15 was investigated by calculating the activation of oxygen molecule. The oxygen molecule can be activated by K /SBA-15 with an energy barrier of 103.2 kJ/mol. In the final state, the activated oxygen atoms become new Lewis acid centers, which are predicted to act as the active sites in the catalytic reactions. This study provides a deep insight into the properties of supported potassium catalysts and offers fundamental information for further research.

Temperature Dynamics for Low-Frequency Raman Spectra of Progesterone, 17α-Hydroxyprogesterone and Cortisone

2010 ◽  
Vol 5 (4) ◽  
pp. 168-172
Author(s):  
Оlga P. Cherkasova ◽  
Vladimir A. Volodin ◽  
Valentina A. Minaeva ◽  
Boris F. Minaev ◽  
Gleb V. Baryshnikov
Keyword(s):  
Raman Spectra ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Low Frequency ◽  
Vibrational Frequencies ◽  
Frequency Region ◽  
Spectral Features ◽  
Temperature Dynamics

The Raman spectra of progesterone, 17α-hydroxyprogesterone and cortisone in the low-frequency region are studied. Several intense spectral features demonstrate clear temperature dynamics in the range of 83 K. Assignment of vibrational frequencies is performed with the use of density functional calculations at the B3LYP/6-31G(d,p) level. The observed spectral features are assigned to vibrations of the whole skeleton including substituents at the С 17 atom

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