Ideal-gas properties of new refrigerants from quantum mechanical ab initio calculations

1993 ◽  
Vol 14 (5) ◽  
pp. 993-1006 ◽  
Author(s):  
K. Lucas ◽  
U. Delfs ◽  
V. Buss ◽  
M. Speis
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Ideal Gas ◽  
Quantum Mechanical ◽  
Gas Properties

scholarly journals Regio-Selectivity Prediction with a Machine-Learned Reaction Representation and On-the-Fly Quantum Mechanical Descriptors

2020 ◽  
Author(s):  
Yanfei Guan ◽  
Connor Coley ◽  
Haoyang wu ◽  
Duminda Ranasinghe ◽  
esther heid ◽  
...  
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Organic Molecules ◽  
New Method ◽  
Quantum Mechanical ◽  
Substitution Reactions ◽  
Reactivity Descriptor ◽  
Constrained Model

<div> <div> <div> <p>We introduce a new method that combines machine-learned reaction representation with selected quantum mechanical descriptors to predict regio-selectivity in general substitution reactions. We construct a reactivity descriptor database based on ab initio calculations of 130k organic molecules, and train a multi-task constrained model to calculate demanded descriptors on-the-fly. </p> </div> </div> </div>

scholarly journals Nitrogen Dissolution in Liquid Ga and Fe: Comprehensive Ab Initio Analysis, Relevance for Crystallization of GaN

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1306
Author(s):  
Jacek Piechota ◽  
Stanislaw Krukowski ◽  
Petro Sadovyi ◽  
Bohdan Sadovyi ◽  
Sylwester Porowski ◽  
...  
Keyword(s):  
Experimental Data ◽  
Molecular Dynamics ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Chemical Potential ◽  
Nitrogen Solubility ◽  
Molecular Nitrogen ◽  
Ideal Gas ◽  
The Difference ◽  
Good Agreement

The dissolution of molecular nitrogen in Ga and Fe was investigated by ab initio calculations and some complementary experiments. It was found that the N bonding inside these solvents is fundamentally different. For Ga, it is between Ga4s and Ga4p and N2p states whereas for Fe this is by N2p to Fe4s, Fe4p and Fe3d states. Accordingly, the energy of dissolution of N2 for arbitrarily chosen starting atomic configurations was 0.535 eV/mol and −0.299 eV/mol for Ga and Fe, respectively. For configurations optimized with molecular dynamics, the difference between the corresponding energy values, 1.107 eV/mol and 0.003 eV/mol, was similarly large. Full thermodynamic analysis of chemical potential was made employing entropy-derived terms in a Debye picture. The entropy-dependent terms were obtained via a normal conditions path to avoid singularity of ideal gas entropy at zero K. Nitrogen solubility as a function of temperature and N2 pressure was evaluated, being much higher for Fe than for Ga. For T=1800 K and p=104 bar, the N concentration in Ga was 3×10−3 at. fr. whereas for Fe, it was 9×10−2 at. fr. in very good agreement with experimental data. It indicates that liquid Fe could be a prospective solvent for GaN crystallization from metallic solutions.

Ab initio calculations of the quantum mechanical hydrogen exchange coupling in the [(C5H5)Ir(PH3)H3]+ complex

1993 ◽  
Vol 115 (13) ◽  
pp. 5861-5862 ◽  
Author(s):  
Abdellah Jarid ◽  
Miquel Moreno ◽  
Agusti Lledos ◽  
Jose M. Lluch ◽  
Juan Bertran
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Exchange Coupling ◽  
Hydrogen Exchange ◽  
Quantum Mechanical

Ideal-gas heat capacities of dimethylsiloxanes from speed-of-sound measurements and ab initio calculations

2007 ◽  
Vol 257 (1) ◽  
pp. 102-113 ◽  
Author(s):  
N.R. Nannan ◽  
P. Colonna ◽  
C.M. Tracy ◽  
R.L. Rowley ◽  
J.J. Hurly
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Speed Of Sound ◽  
Ideal Gas ◽  
Heat Capacities

Quantum mechanical tunnelling in the processes D + H2 → DH + H and CH4 + H → CH3 + H2. Eckart's tunnelling corrections for rate constants given by ab initio calculations

1979 ◽  
Vol 44 (12) ◽  
pp. 3452-3457 ◽  
Author(s):  
Petr Čársky
Keyword(s):  
Transition State ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Rate Constants ◽  
Transition State Theory ◽  
State Theory ◽  
Quantum Mechanical ◽  
Rate Data ◽  
Dimensional Approach ◽  
One Dimensional

Results of the best reported ab initio calculations are used to evaluate the rate constants of the title processes by means of the transition state theory. The computed rate constants are corrected for the quantum mechanical tunnelling by the Eckart's one-dimensional approach and comparison is made with experimental rate data

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