Effect of polarization functions and electron correlation on the cyclopropylcarbinyl cation and bicyclobutonium ion (C4H7+) potential energy surface

1986 ◽  
Vol 90 (21) ◽  
pp. 4908-4910 ◽  
Author(s):  
Michael L. McKee
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Electron Correlation ◽  
Energy Surface ◽  
Polarization Functions

scholarly journals Combining EXAFS and Computer Simulations to Refine the Structural Description of Actinyls in Water

Molecules ◽  
2020 ◽  
Vol 25 (22) ◽  
pp. 5250
Author(s):  
Sergio Pérez-Conesa ◽  
José M. Martínez ◽  
Rafael R. Pappalardo ◽  
Enrique Sánchez Marcos
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Force Field ◽  
Electron Correlation ◽  
Energy Surface ◽  
Open Shell ◽  
Complex Signal ◽  
Quantum Mechanical ◽  
Structural Description ◽  
Exafs Spectra

EXAFS spectroscopy is one of the most used techniques to solve the structure of actinoid solutions. In this work a systematic analysis of the EXAFS spectra of four actinyl cations, [UO2]2+, [NpO2]2+, [NpO2]+ and [PuO2]2+ has been carried out by comparing experimental results with theoretical spectra. These were obtained by averaging individual contributions from snapshots taken from classical Molecular Dynamics simulations which employed a recently developed [AnO2]2+/+ –H2O force field based on the hydrated ion model using a quantum-mechanical (B3LYP) potential energy surface. Analysis of the complex EXAFS signal shows that both An-Oyl and An-OW single scattering paths as well as multiple scattering ones involving [AnO2]+/2+ molecular cation and first-shell water molecules are mixed up all together to produce a very complex signal. Simulated EXAFS from the B3LYP force field are in reasonable agreement for some of the cases studied, although the k= 6–8 Å−1 region is hard to be reproduced theoretically. Except uranyl, all studied actinyls are open-shell electron configurations, therefore it has been investigated how simulated EXAFS spectra are affected by minute changes of An-O bond distances produced by the inclusion of static and dynamic electron correlation in the quantum mechanical calculations. A [NpO2]+−H2O force field based on a NEVPT2 potential energy surface has been developed. The small structural changes incorporated by the electron correlation on the actinyl aqua ion geometry, typically smaller than 0.07 Å, leads to improve the simulated spectrum with respect to that obtained from the B3LYP force field. For the other open-shell actinyls, [NpO2]2+ and [PuO2]2+, a simplified strategy has been adopted to improve the simulated EXAFS spectrum. It is computed taking as reference structure the NEVPT2 optimized geometry and including the DW factors of their corresponding MD simulations employing the B3LYP force field. A better agreement between the experimental and the simulated EXAFS spectra is found, confirming the a priori guess that the inclusion of dynamic and static correlation refine the structural description of the open-shell actinyl aqua ions.

Understanding the hcp anisotropy in Cd and Zn: the role of electron correlation in determining the potential energy surface

2010 ◽  
Vol 12 (3) ◽  
pp. 681-687 ◽  
Author(s):  
Nicola Gaston ◽  
Dirk Andrae ◽  
Beate Paulus ◽  
Ulrich Wedig ◽  
Martin Jansen
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Electron Correlation ◽  
Energy Surface

Potential Energy Surface Including Electron Correlation for the Chemical F + H2 → FH + H I. Preliminary Surface

1972 ◽  
Vol 56 (9) ◽  
pp. 4626-4631 ◽  
Author(s):  
Charles F. Bender ◽  
Peter K. Pearson ◽  
Stephen V. O'Neil ◽  
Henry F. Schaefer
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Electron Correlation ◽  
Energy Surface

scholarly journals Ne–H–H potential energy surface including electron correlation

1975 ◽  
Vol 63 (5) ◽  
pp. 1741-1747 ◽  
Author(s):  
John W. Birks ◽  
Harold S. Johnston ◽  
Henry F. Schaefer
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Electron Correlation ◽  
Energy Surface

Potential Energy Surface Including Electron Correlation for F + H2 rarr FH + H: Refined Linear Surface

Science ◽  
1972 ◽  
Vol 176 (4042) ◽  
pp. 1412-1414 ◽  
Author(s):  
C. F. Bender ◽  
S. V. O'Neil ◽  
P. K. Pearson ◽  
H. F. Schaefer
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Electron Correlation ◽  
Energy Surface
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