Coupled-cluster based basis sets for valence correlation calculations. New primitives, frozen atomic natural orbitals, and basis sets from double to hextuple zeta for atoms H, He, and B–Ne

2018 ◽  
Vol 149 (6) ◽  
pp. 064105 ◽  
Author(s):  
Daniel Claudino ◽  
Rodney J. Bartlett
Keyword(s):  
Basis Sets ◽  
Coupled Cluster ◽  
Natural Orbitals ◽  
Atomic Natural Orbitals

scholarly journals Extrapolation of Atomic Natural Orbitals of basis set to complete basis set limit

2017 ◽  
Vol 10 (2) ◽  
pp. 159-164
Author(s):  
Jaroslav Granatier
Keyword(s):  
Electron Correlation ◽  
Quantitative Agreement ◽  
Basis Set ◽  
Basis Sets ◽  
Natural Orbitals ◽  
Benchmark Data ◽  
Complete Basis ◽  
Complete Basis Set ◽  
Complete Basis Set Limit ◽  
Atomic Natural Orbitals

AbstractRelativistic Atomic Natural Orbitals (ANO-RCC) are extrapolated to the complete basis set limit. ANO-RCC-VXZP (X = D, T, Q) basis sets were extrapolated using standard extrapolation techniques. Five noncovalent complexes, characterized by hydrogen, dispersion and halogen interactions, were chosen. Accurate description of the studied complexes is allowed only after the inclusion of electron correlation and large basis sets which have to include polarization and diffuse functions. Results are in quantitative agreement with the benchmark data obtained by standard aug-cc-pVXZ-DK (X = D, T, Q) basis sets considering chemical accuracy of ±1 kcal/mol.

Theoretical analysis of the (HNO)2, (HNO···HNS), and (HNS)2 dimers — A case of red and blue shifts of N–H stretching frequency

2010 ◽  
Vol 88 (8) ◽  
pp. 849-857 ◽  
Author(s):  
Nguyen Tien Trung ◽  
Tran Thanh Hue ◽  
Minh Tho Nguyen
Keyword(s):  
Hydrogen Bond ◽  
Quantum Chemical ◽  
Bond Formation ◽  
Blue Shift ◽  
Proton Donor ◽  
Basis Sets ◽  
Coupled Cluster ◽  
Hydrogen Bond Formation ◽  
Length Contraction ◽  
Moller Plesset

The hydrogen-bonded interactions in the simple (HNZ)2 dimers, with Z = O and S, were investigated using quantum chemical calculations with the second-order Møller–Plesset perturbation (MP2), coupled-cluster with single, double (CCSD), and triple excitations (CCSD(T)) methods in conjunction with the 6-311++G(2d,2p), aug-cc-pVDZ, and aug-cc-pVTZ basis sets. Six-membered cyclic structures were found to be stable complexes for the dimers (HNO)2, (HNS)2, and (HNO–HNS). The pair (HNS)2 has the largest complexation energy (–11 kJ/mol), and (HNO)2 the smallest one (–9 kJ/mol). A bond length contraction and a frequency blue shift of the N–H bond simultaneously occur upon hydrogen bond formation of the N–H···S type, which has rarely been observed before. The stronger the intramolecular hyperconjugation and the lower the polarization of the X–H bond involved as proton donor in the hydrogen bond, the more predominant is the formation of a blue-shifting hydrogen bond.

Application of multireference linearized coupled-cluster theory to atomic and molecular systems

2018 ◽  
Vol 17 (02) ◽  
pp. 1850016 ◽  
Author(s):  
Jiang Yi ◽  
Feiwu Chen
Keyword(s):  
Ground State ◽  
Basis Sets ◽  
Coupled Cluster ◽  
Vibration Frequencies ◽  
Electron Affinities ◽  
Proton Affinities ◽  
Coupled Cluster Theory ◽  
Molecular Systems ◽  
Ground State Energies ◽  
Second Order Perturbation Theory

Applications of the multireference linearized coupled-cluster single-doubles (MRLCCSD) to atomic and molecular systems have been carried out. MRLCCSD is exploited to calculate the ground-state energies of HF, H2O, NH3, CH4, N2, BF, and C2with basis sets, cc-pVDZ, cc-pVTZ and cc-pVQZ. The equilibrium bond lengths and vibration frequencies of HF, HCl, Li2, LiH, LiF, LiBr, BH, and AlF are computed with MRLCCSD and compared with the experimental data. The electron affinities of F and CH as well as the proton affinities of H2O and NH3are also calculated with MRLCCSD. These results are compared with the results produced with second-order perturbation theory, linearized coupled-cluster doubles (LCCD), coupled-cluster doubles (CCD), coupled-cluster singles and doubles (CCSD), CCSD with perturbative triples correction (CCSD(T)). It is shown that all results obtained with MRLCCSD are reliable and accurate.

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