scholarly journals Toward a W4-F12 approach: Can explicitly correlated and orbital-based ab initio CCSD(T) limits be reconciled?

2016 ◽  
Vol 144 (21) ◽  
pp. 214101 ◽  
Author(s):  
Nitai Sylvetsky ◽  
Kirk A. Peterson ◽  
Amir Karton ◽  
Jan M. L. Martin
Keyword(s):  
Ab Initio ◽  
Explicitly Correlated

scholarly journals Rethinking the X− + CH3Y [X = OH, SH, CN, NH2, PH2; Y = F, Cl, Br, I] SN2 reactions

2019 ◽  
Vol 21 (15) ◽  
pp. 7924-7931 ◽  
Author(s):  
Domonkos A. Tasi ◽  
Zita Fábián ◽  
Gábor Czakó
Keyword(s):  
Ab Initio ◽  
Sn2 Reactions ◽  
Explicitly Correlated ◽  
Leaving Groups

Explicitly-correlated ab initio computations reveal novel inversion and retention pathways for several SN2 reactions with different nucleophiles and leaving groups.

scholarly journals Isolation of a Halogen-Bonded Complex Formed between Methane and Chlorine Monofluoride and Characterisation by Rotational Spectroscopy and Ab Initio Calculations

Molecules ◽  
2019 ◽  
Vol 24 (23) ◽  
pp. 4257 ◽  
Author(s):  
Anthony C. Legon ◽  
David G. Lister ◽  
John H. Holloway ◽  
Devendra Mani ◽  
Elangannan Arunan
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Internal Rotation ◽  
Halogen Bond ◽  
Spectroscopic Constants ◽  
Bond Critical Point ◽  
Equilibrium Geometry ◽  
Rotational Spectrum ◽  
Pulsed Jet ◽  
Explicitly Correlated

A halogen-bonded complex formed between methane and chlorine monofluoride has been isolated in the gas phase before the reaction between the components and has been characterised through its rotational spectrum, which is of the symmetric-top type but only exhibits K = 0 type transitions at the low effective temperature of the pulsed-jet experiment. Spectroscopic constants for two low-lying states that result from internal rotation of the CH4 subunit were detected for each of the two isotopic varieties H4C···35ClF and H4C···37ClF and were analysed to show that ClF lies on the symmetry axis with Cl located closer than F to the C atom, at the distance r0(C···Cl) ≅ 3.28 Å and with an intermolecular stretching force constant kσ ≅ 4 N m−1. Ab initio calculations at the explicitly correlated level CCSD(T)(F12c)/cc-pVTZ-F12 show that in the equilibrium geometry, the ClF molecule lies along a C3 axis of CH4 and Cl is involved in a halogen bond. The Cl atom points at the nucleophilic region identified on the C3 axis, opposite the unique C–H bond and somewhere near the C atom and the tetrahedron face centre, with re(C···Cl) = 3.191 Å. Atoms-in-molecules (AIM) theory shows a bond critical point between Cl and C, confirming the presence of a halogen bond. The energy that is required to dissociate the complex from the equilibrium conformation into its CH4 and ClF components is only De ≅ 5 kJ mol−1. A likely path for the internal rotation of the CH4 subunit is identified by calculations at the same level of theory, which also provide the variation of the energy of the system as a function of the motion along that path. The barrier to the motion along the path is only ≅ 20 cm−1.

scholarly journals The S66x8 benchmark for noncovalent interactions revisited: explicitly correlated ab initio methods and density functional theory

2016 ◽  
Vol 18 (31) ◽  
pp. 20905-20925 ◽  
Author(s):  
Brina Brauer ◽  
Manoj K. Kesharwani ◽  
Sebastian Kozuch ◽  
Jan M. L. Martin
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Noncovalent Interactions ◽  
Ab Initio Methods ◽  
Functional Theory ◽  
Explicitly Correlated

The S66x8 dataset for noncovalent interactions of biochemical relevance has been re-examined by means of CCSD(F12*)(T), DFT, and SAPT methods.

Conventional and Explicitly Correlated ab Initio Benchmark Study on Water Clusters: Revision of the BEGDB and WATER27 Data Sets

2017 ◽  
Vol 13 (7) ◽  
pp. 3136-3152 ◽  
Author(s):  
Debashree Manna ◽  
Manoj K. Kesharwani ◽  
Nitai Sylvetsky ◽  
Jan M. L. Martin
Keyword(s):  
Ab Initio ◽  
Water Clusters ◽  
Data Sets ◽  
Benchmark Study ◽  
Explicitly Correlated
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