Quantifying multiple-body interaction terms in H-bonded HCN chains with many-body perturbation/coupled-cluster theories

Abstract

Many-body perturbation/coupled-cluster calculations have been carried out to investigate the multiple-body energy terms and their contribution to the interaction energy of linear (HCN)N chains. All minimum energy geometries of the clusters (N=2–7) are obtained at the second-order many-body perturbation (MP2) levels of theory. Electron correlation and cooperative effects in the C–H⋯N hydrogen bonds are also quantitatively characterized during the aggregation process. It is found that the two- and three-body terms account for nearly all of the total interaction energy, but all high-body terms increase with the size of the cluster. Detailed numerical values are given for all the many-body contributions of the (HCN)N chains. Electron correlation effects are found to be important for the two- and three-body terms but have decreased importance for the higher-body terms. Cooperative effects are also investigated for the binding energy and dipole moment. The dipole moments of the HCN oligomers are larger than the sum of the individual monomers with differences ranging between 12% (N=2) and 28% (N=7). The limiting values for the binding energy and dipole moment of (HCN)N, per monomer, corresponding to very large N values, are estimated to be 22.9 kJ/mol and 3.87 D, per monomer, respectively. These results correspond to cooperative contributions of 5.8 kJ/mol to the energy, and 1.0 D to the dipole moment.

Importance of electron correlation effects and basis set superposition error in calculations of interaction energies and interaction-induced electric properties in hydrogen-bonded complexes: a model study

“…The MP2/6-311? ?G(d,p) results of Rivelino et al [18] for the n = 2, 3, 4 clusters are well bellow our MP2 values, maybe due to the basis set they use. And our values considerably improve those calculated by Adrian-Scotto and Vasilescu [19], both with respect to method and basis sets.…”

“…This conclusion has to be taken with caution, considering the above-mentioned differences between the experimental and the theoretical geometries. The best previously available theoretical result [18], obtained with the CCSD(T) method and the aug-cc-pVTZ basis set, is closer to the fs and fl results than to the ds and dl. From Ref.…”

“…From Ref. [18], we can estimate CCSD(T) aug-cc-pVTZ interaction energies for the n = 3 and n = 4 complexes as -10.11 and -15.97 kcal/mol, respectively. We do this by correcting the MP2/6-311?…”

“…Rivelino et al [18] used a hierarchy of methods (HF, MP2, MP3, MP4, CCSD and CCSD(T)) and up to the augcc-pVTZ basis set to evaluate the (HCN) 2 interaction energy. For the (HCN) 3 and the (HCN) 4 complexes, they employed a smaller basis set, i.e., the 6-311?…”

SAPT: ligação de hidrogênio ou interação de van der Waals?

“…Como esperado, a energia proveniente do potencial de troca de spins (E Ex (12) ) é sempre positiva, por se tratar de um termo repulsivo derivado do princípio da exclusão de Pauli. Embora o sistema (f) apresente uma contribuição ínfima de -1,71 kcal/mol para a energia eletrostática E (12) C,Resp , comparativamente os valores de -1,51 e -1,26 kcal/mol relacionados aos termos das energias de dispersão E D (20) 129 Canuto et al, 130 Frontera et al, 131 Parra et al 132 e em recente comunicação de Bauer e Spange.…”