scholarly journals Solution of a Puzzle: High-Level Quantum-Chemical Treatment of Pseudocontact Chemical Shifts Confirms Classic Semiempirical Theory

2020 ◽  
Vol 11 (20) ◽  
pp. 8735-8744
Author(s):  
Lucas Lang ◽  
Enrico Ravera ◽  
Giacomo Parigi ◽  
Claudio Luchinat ◽  
Frank Neese
Keyword(s):  
Chemical Treatment ◽  
Quantum Chemical ◽  
Chemical Shifts ◽  
Semiempirical Theory ◽  
High Level

scholarly journals RELATIVISTIC CALCULATIONS OF MAGNETORESONSONIC PARAMETERS IN STRUCTURAL STUDIES OF ELEMENTENTORGANIC COMPOUNDS

2020 ◽  
Vol 2018 (1) ◽  
pp. 17-18
Author(s):  
Leonid Krivdin
Keyword(s):  
Quantum Chemical ◽  
Organophosphorus Compounds ◽  
Chemical Shifts ◽  
Relativistic Effects ◽  
Basis Set ◽  
Spin Interaction ◽  
Chemical Calculation ◽  
Structural Studies ◽  
Wide Range ◽  
High Level

Systematic structural studies were carried out in a wide range of nitrogen, silicon, phosphorus, selenium, and organophosphorus compounds by quantum-chemical calculations of a high level of isotropic absolute magnetic-shielding constants (chemical shifts) and spin-spin interaction constants involving 1H, 13C, 15N, 19F, 29Si, 31P, 77Se and 125Te in comparison with the experiment. The analysis of the factors determining the accuracy of the quantum chemical calculation of the discussed magnetoresonance parameters including the level of the theory and the quality of the basis set, the influence of the medium, vibrational corrections, and relativistic effects are analyzed.

scholarly journals Quantum chemical calculations of31P NMR chemical shifts: scopes and limitations

2015 ◽  
Vol 17 (10) ◽  
pp. 6976-6987 ◽  
Author(s):  
Shamil K. Latypov ◽  
Fedor M. Polyancev ◽  
Dmitry G. Yakhvarov ◽  
Oleg G. Sinyashin
Keyword(s):  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Organophosphorus Compounds ◽  
Chemical Shifts ◽  
Nmr Chemical Shifts ◽  
High Level

High level of theory is not necessarily needed to obtain rather accurate predictions of31P chemical shifts by GIAO method. For example, the PBE1PBE/6-311G(2d,2p)//PBE1PBE/6-31+G(d) combination allowed to obtain good results for variety of middle-size organophosphorus compounds (M= 200–700 Da).

World of van der Waals Species

1993 ◽  
Vol 58 (7) ◽  
pp. 1465-1475
Author(s):  
Pavel Hobza ◽  
Rudolf Zahradník
Keyword(s):  
Chemical Treatment ◽  
Quantum Chemical ◽  
Van Der Waals ◽  
Real Challenge

Van der Waals species (molecules, ions, radicals) attract the attention of chemists, chemical physicists and molecular biologists. Study of these systems presents a real challenge for both experimentalists and theorists. The main features of the contemporary possibilities for quantum chemical treatment are illustrated mostly on systems studied in the authors' laboratory. Prospects in the area are briefly outlined.

scholarly journals Real-time prediction of 1H and 13C chemical shifts with DFT accuracy using a 3D graph neural network

2021 ◽  
Author(s):  
Yanfei Guan ◽  
S. V. Shree Sowndarya ◽  
Liliana C. Gallegos ◽  
Peter C. St. John ◽  
Robert S. Paton
Keyword(s):  
Neural Network ◽  
Real Time ◽  
Quantum Chemical ◽  
Organic Molecules ◽  
Chemical Shifts ◽  
13C Chemical Shifts ◽  
Time Prediction ◽  
Nmr Data ◽  
Proton Chemical Shifts

From quantum chemical and experimental NMR data, a 3D graph neural network, CASCADE, has been developed to predict carbon and proton chemical shifts. Stereoisomers and conformers of organic molecules can be correctly distinguished.

Structural Characterization of Natural Products By Means of Quantum Chemical Calculations of NMR Parameters: New insights

2021 ◽  
Author(s):  
Fabio Luiz Paranhos Costa ◽  
Ana Carolina Ferreira de Albuquerque ◽  
Rodolfo Goetze Fiorot ◽  
Luciano Morais Lião ◽  
Lucas Haidar Martorano ◽  
...  
Keyword(s):  
Natural Products ◽  
Structural Characterization ◽  
Quantum Chemical ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Nmr Parameters ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling

The calculation of NMR parameters for natural products was pioneered by Bifulco and coworkers in 2002. Since then, modelling 1H and 13C chemical shifts and spin-spin coupling constants for this...

Excitons in poly(para phenylene vinylene): a quantum-chemical perspective based on high-level ab initio calculations

2016 ◽  
Vol 18 (4) ◽  
pp. 2548-2563 ◽  
Author(s):  
Stefanie A. Mewes ◽  
Jan-Michael Mewes ◽  
Andreas Dreuw ◽  
Felix Plasser
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Quantum Chemical ◽  
Phenylene Vinylene ◽  
High Level ◽  
Quantum Chemical Computations

Exciton analyses of high-level quantum-chemical computations for poly(paraphenylene vinylene) reveal the nature of the excitonic bands in PPV oligomers.

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