Mechanism of primary photochemistry reactions in organic molecules using quantum chemistry methods

1998 ◽  
Author(s):  
Georgy V. Mayer ◽  
O. K. Bazyl ◽  
Victor Y. Artyukhov
Keyword(s):  
Quantum Chemistry ◽  
Organic Molecules ◽  
Primary Photochemistry

scholarly journals QM-sym, a symmetrized quantum chemistry database of 135 kilo molecules

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Jiechun Liang ◽  
Yanheng Xu ◽  
Rulin Liu ◽  
Xi Zhu
Keyword(s):  
Quantum Chemistry ◽  
Organic Molecules ◽  
Materials Science ◽  
Stable State ◽  
Chemical Properties ◽  
Science Research ◽  
Orbital Symmetry ◽  
Large Molecules ◽  
Homo Lumo ◽  
Machine Learning Models

AbstractApplying deep learning methods in materials science research is an important way of solving the time-consuming problems of typical ab initio quantum chemistry methodology, but due to the size of large molecules, large and uncharted fields still exist. Implementing symmetry information can significantly reduce the calculation complexity of structures, as they can be simplified to the minimum symmetric units. Because there are few quantum chemistry databases that include symmetry information, we constructed a new one, named QM-sym, by designing an algorithm to generate 135k organic molecules with the Cnh symmetry composite. Those generated molecules were optimized to a stable state using Gaussian 09. The geometric, electronic, energetic, and thermodynamic properties of the molecules were calculated, including their orbital degeneracy states and orbital symmetry around the HOMO-LUMO. The basic symmetric units were also included. This database p rovides consistent and comprehensive quantum chemical properties for structures with Cnh symmetries. QM-sym can be used as a benchmark for machine learning models in quantum chemistry or as a dataset for training new symmetry-based models.

scholarly journals Photoinduced C–H bond fission in prototypical organic molecules and radicals

2019 ◽  
Vol 21 (26) ◽  
pp. 13880-13901 ◽  
Author(s):  
Michael N. R. Ashfold ◽  
Rebecca A. Ingle ◽  
Tolga N. V. Karsili ◽  
Jingsong Zhang
Keyword(s):  
Organic Molecules ◽  
Current Knowledge ◽  
Primary Photochemistry ◽  
Hydrocarbon Molecules

We survey and assess current knowledge regarding the primary photochemistry of hydrocarbon molecules and radicals.

scholarly journals Pressure-driven phase transition mechanisms revealed by quantum chemistry: l-serine polymorphs

2017 ◽  
Vol 19 (9) ◽  
pp. 6671-6676 ◽  
Author(s):  
Denis A. Rychkov ◽  
Jernej Stare ◽  
Elena V. Boldyreva
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Quantum Chemistry ◽  
Organic Molecules ◽  
Computational Approach ◽  
Small Organic Molecules ◽  
Pressure Driven

The present study delivers a computational approach for the understanding of the mechanism of phase transitions between polymorphs of small organic molecules.

High Resolution Replication of Organoclay Surfaces

1982 ◽  
Vol 40 ◽  
pp. 576-577
Author(s):  
W. W. Barker ◽  
W. E. Rigsby ◽  
V. J. Hurst ◽  
W. J. Humphreys
Keyword(s):  
Clay Mineral ◽  
Organic Molecule ◽  
Organic Molecules ◽  
X Ray Diffraction ◽  
Xrd Pattern ◽  
X Ray ◽  
Naturally Occurring ◽  
Silicate Layers ◽  
Mineral Identification

Experimental clay mineral-organic molecule complexes long have been known and some of them have been extensively studied by X-ray diffraction methods. The organic molecules are adsorbed onto the surfaces of the clay minerals, or intercalated between the silicate layers. Natural organo-clays also are widely recognized but generally have not been well characterized. Widely used techniques for clay mineral identification involve treatment of the sample with H2 O2 or other oxidant to destroy any associated organics. This generally simplifies and intensifies the XRD pattern of the clay residue, but helps little with the characterization of the original organoclay. Adequate techniques for the direct observation of synthetic and naturally occurring organoclays are yet to be developed.

Direct phase determination in electron crystallography: small organic molecules

1992 ◽  
Vol 50 (2) ◽  
pp. 1166-1167
Author(s):  
Douglas L. Dorset
Keyword(s):  
Organic Molecules ◽  
Data Sets ◽  
Temperature Structure ◽  
3D Analysis ◽  
Intensity Data ◽  
Electron Crystallography ◽  
Phase Determination ◽  
Measured Intensity ◽  
3D Data

The quantitative use of electron diffraction intensity data for the determination of crystal structures represents the pioneering achievement in the electron crystallography of organic molecules, an effort largely begun by B. K. Vainshtein and his co-workers. However, despite numerous representative structure analyses yielding results consistent with X-ray determination, this entire effort was viewed with considerable mistrust by many crystallographers. This was no doubt due to the rather high crystallographic R-factors reported for some structures and, more importantly, the failure to convince many skeptics that the measured intensity data were adequate for ab initio structure determinations.We have recently demonstrated the utility of these data sets for structure analyses by direct phase determination based on the probabilistic estimate of three- and four-phase structure invariant sums. Examples include the structure of diketopiperazine using Vainshtein's 3D data, a similar 3D analysis of the room temperature structure of thiourea, and a zonal determination of the urea structure, the latter also based on data collected by the Moscow group.

A MOLECULAR DYNAMICS STUDY OF ELECTRONIC SPUTTERING OF LARGE ORGANIC MOLECULES

1989 ◽  
Vol 50 (C2) ◽  
pp. C2-33-C2-35 ◽  
Author(s):  
D. FENYÖ ◽  
B. U.R. SUNDQVIST ◽  
B. KARLSSON ◽  
R. E. JOHNSON
Keyword(s):  
Molecular Dynamics ◽  
Organic Molecules

Quantum Chemistry.

1958 ◽  
Vol 17 (3_4) ◽  
pp. 279-280
Author(s):  
Th. Förster
Keyword(s):  
Quantum Chemistry
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