scholarly journals Molecular vibrational frequencies from analytic Hessian of constrained nuclear–electronic orbital density functional theory

2021 ◽  
Vol 154 (24) ◽  
pp. 244110
Author(s):  
Xi Xu ◽  
Yang Yang
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Vibrational Frequencies ◽  
Functional Theory ◽  
Orbital Density

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.

scholarly journals Experimental and Density Functional Theory Characteristics of Ibrutinib, a Bruton’s Kinase Inhibitor Approved for Leukemia Treatment

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Ali I. Ismail
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Kinase Inhibitor ◽  
Theoretical Calculations ◽  
Dft Method ◽  
Vibrational Frequencies ◽  
Basis Sets ◽  
Electronic Transitions ◽  
Functional Theory ◽  
Leukemia Treatment

Ibrutinib, a Bruton’s tyrosine kinase that plays an essential role in the B-cell development and cancer cells, has been recently approved to treat chronic, lymphocytic, and other types of leukemia. This study focused on investigating ibrutinib by its electronic transitions, vibrational frequencies, and electrospray mass spectra. The experimental peaks for electronic spectrum were found at 248.0 and 281.0 nm, whereas the νC = 0 stretching frequency was found at 1652.4 and 1639.19 cm−1. These experimental properties were compared with the corresponding theoretical calculations in which density functional theory was applied. The optimized structure was obtained with the calculations using a hybrid function (B3LYP) and high-level basis sets [6-311G++(d,p)]. Most of the calculated vibrational frequencies showed a relatively good agreement with the experimental ones. The electronic transitions of ibrutinib calculated using time-dependent DFT method were performed at two different solvation methods: PCM and SMD. The mass spectrum of ibrutinib, its fragments, and its isotopic pattern agreed well with the expected spectra.

STRUCTURAL AND ELECTRONIC PROPERTIES OF (CnLi)+ CLUSTER IONS

2005 ◽  
Vol 16 (02) ◽  
pp. 271-280
Author(s):  
EFE YAZGAN ◽  
ŞAKIR ERKOÇ
Keyword(s):  
Density Functional Theory ◽  
Electronic Properties ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Vibrational Frequencies ◽  
Cluster Ions ◽  
Functional Theory ◽  
B3lyp Level ◽  
Structural And Electronic Properties

The structural and electronic properties of ( C n Li )+ cluster ions with n =1–6 and n =20 have been investigated by performing density functional theory calculations at B3LYP level. The vibrational frequencies of the clusters are also calculated.

Further developments in the local-orbital density-functional-theory tight-binding method

2001 ◽  
Vol 64 (19) ◽  
Author(s):  
James P. Lewis ◽  
Kurt R. Glaesemann ◽  
Gregory A. Voth ◽  
Jürgen Fritsch ◽  
Alexander A. Demkov ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Tight Binding ◽  
Functional Theory ◽  
Tight Binding Method ◽  
Orbital Density
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