Interaction energies of dispersion-bound methane dimer from coupled cluster method at complete basis set limit

2009 ◽  
Vol 897 (1-3) ◽  
pp. 90-94 ◽  
Author(s):  
Arvin Huang-Te Li ◽  
Sheng D. Chao
Keyword(s):  
Basis Set ◽  
Cluster Method ◽  
Coupled Cluster ◽  
Interaction Energies ◽  
Coupled Cluster Method ◽  
Complete Basis ◽  
Complete Basis Set ◽  
Complete Basis Set Limit

scholarly journals Towards the Search for Thallium Nuclear Schiff Moment in Polyatomic Molecules: Molecular Properties of Thallium Monocyanide (TlCN)

Atoms ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 62 ◽  
Author(s):  
A. Kudrin ◽  
A. Zaitsevskii ◽  
T. Isaev ◽  
D. Maison ◽  
L. Skripnikov
Keyword(s):  
Inner Core ◽  
Molecular Properties ◽  
Basis Set ◽  
Cluster Method ◽  
Coupled Cluster ◽  
The Core ◽  
Complete Basis Set ◽  
Core Electrons ◽  
Complete Basis Set Limit ◽  
Potential Energy Minimum

Molecular properties of the thallium monocyanide (Tl·CN) system in its ground electronic state are studied using high-precision ab initio relativistic two-component pseudopotential replacing 60 inner-core electrons of Tl. A relativistic coupled-cluster method with single, double and perturbative triple amplitudes is employed to account for electronic correlations. Extrapolation of results to the complete basis set limit is used for all studied properties. The global potential energy minimum of Tl·CN corresponds to the linear cyanide (TlCN) isomer, while the non-rigid isocyanide-like (TlNC) structure lies by approximately 11 kJ/mol higher in energy. The procedure of restoration of the wavefunction in the “core” region of Tl atom was applied to calculate the interaction of the Tl nuclear Schiff moment with electrons. The parameter X of the interaction of the Tl nuclear Schiff moment with electrons in the linear TlCN molecule equals 7150 a.u. The prospects of using the TlCN molecule for the experimental detection of the nuclear Schiff moment are discussed.

Group IIIa Hydrides XH2 and XH2- (X = B, Al, Ga): Electron Affinities and Singlet-Triplet Splittings Revisited

2003 ◽  
Vol 68 (1) ◽  
pp. 75-88 ◽  
Author(s):  
Ivan Černušák ◽  
Alena Zavažanová ◽  
Juraj Raab ◽  
Pavel Neogrády
Keyword(s):  
Ground State ◽  
Basis Set ◽  
Basis Sets ◽  
Coupled Cluster ◽  
Electron Affinities ◽  
Complete Basis ◽  
Complete Basis Set ◽  
Order Of Magnitude ◽  
Complete Basis Set Limit ◽  
Cluster Methods

Geometries, electron affinities (EA) and singlet-triplet (S-T) splittings of XH2/XH2- molecules (X = B, Al, Ga) are calculated by coupled-cluster methods, using the sequence of basis sets. The EA values and S-T splittings for aluminium and gallium dihydrides are an order of magnitude larger (in absolute values) than those for boron. For boron and aluminium dihydrides, two types of extrapolations towards complete basis set limit are applied, leading to EA = 0.24 eV, ST = -0.01 eV (BH2), and EA = 1.10 eV, ST = -0.62 eV. The best calculated values for gallium dihydrides are EA = 1.13 eV and ST = -0.74 eV. All three S-T splittings favour singlet as the ground state, although the S-T splittings of BH2- is exceptionally small. In addition, vertical electron affinities and vertical electron detachments are reported for these molecules.

From CCSD(T)/aug-cc-pVTZ-J to CCSD(T) complete basis set limit isotropic nuclear magnetic shieldings via affordable DFT/CBS calculations

2011 ◽  
Vol 49 (5) ◽  
pp. 231-236 ◽  
Author(s):  
Teobald Kupka ◽  
Michał Stachów ◽  
Marzena Nieradka ◽  
Jakub Kaminsky ◽  
Tadeusz Pluta ◽  
...  
Keyword(s):  
Basis Set ◽  
Complete Basis ◽  
Complete Basis Set ◽  
Complete Basis Set Limit ◽  
Nuclear Magnetic

scholarly journals Quantum Calculations to Estimate the Heat of Hydrogenation Theoretically

2020 ◽  
Author(s):  
Ali Amir Khairbek
Keyword(s):  
Unsaturated Hydrocarbon ◽  
Experimental Results ◽  
Basis Set ◽  
Good Linear ◽  
Complete Basis ◽  
Complete Basis Set ◽  
Complete Basis Set Limit ◽  
The Mean ◽  
Experimental Values ◽  
Linear Correlations

Standard enthalpies of hydrogenation of 29 unsaturated hydrocarbon compounds were calculated in the gas phase by CCSD(T) theory with complete basis set cc-pVXZ, where X = DZ, TZ, as well as by complete basis set limit extrapolation. Geometries of reactants and products were optimized at the M06-2X/6-31g(d) level. This M06-2X geometries were used in the CCSD(T)/cc-pVXZ//M06-2X/6-31g(d) and cc-pV(DT)Z extrapolation calculations. (MAD) the mean absolute deviations of the enthalpies of hydrogenation between the calculated and experimental results that range from 8.8 to 3.4 kJ mol−1 based on the Comparison between the calculation at CCSD(T) and experimental results. The MAD value has improved and decreased to 1.5 kJ mol−1 after using complete basis set limit extrapolation. The deviations of the experimental values are located inside the “chemical accuracy” (±1 kcal mol−1 ≈ ±4.2 kJ mol−1) as some results showed. A very good linear correlations between experimental and calculated enthalpies of hydro-genation have been obtained at CCSD(T)/cc-pVTZ//M06-2X/6-31g(d) level and CCSD(T)/cc-pV(DT)Z extrapolation levels (SD =2.11 and 2.12 kJ mol−1, respectively).

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