The use of the MP2 aproximation with a small basis set is known to reproduce interaction energies for weakly bonded complexes with fairly good accuracy, when corrected for the BSSE. However, it is always a good practice to compare the results obtained in this fashion with higher-level calculations whenever they are computationally allowable. In the case of the BTT-aminoacid complexes studied in...

Inmany applications, the cumulative distribution function (cdf) FQN of a positively weighted sum of N i.i.d. chi-squared randomvariables QN is required.Although there is no known closed-form solution for FQN , there are many good approximations. When computational efficiency is not an issue, Imhof’smethod provides a good solution. However, when both the accuracy of the approximation and the spe...

The hydrogen bond (H-bond) energies are evaluated for 18 molecular crystals with 28 moderate and strong O-H···O bonds using the approaches based on the electron density properties, which are derived from the B3LYP/6-311G** calculations with periodic boundary conditions. The approaches considered explore linear relationships between the local electronic kinetic G(b) and potential V(b) densities ...

The infrared spectra of the formic acid-water complexes isolated in argon matrices are reported. Both supersonic jet expansion and a conventional effusive source followed by trapping in solid argon at 10K are used to obtain the matrices. The experimental IR spectra are compared to the data obtained from high level ab initio (MP2) and DFT (B3LYP) calculations with 6-311++G(d,p) and aug-cc-pVTZ b...

Interaction energies of a water molecule with a model Cu(111) surface were investigated using the cluster model approach and high-level ab initio methods. Potential energy scans were calculated for a Cu10 model cluster and a water molecule with a second-order Møller-Plesset (MP2) method using a RECP/6-31+G* basis set and counterpoise correction (CP) for the basis set superposition error (BSSE)....

Os movimentos de grande amplitude no complexo HF...ClF foram estudados teoricamente. Na solução das equações dinâmicas foi utilizada uma superfície de energia potencial ab initio calculada a nível MP2/DZ+(2d1f/2p1d)//HF/DZP, incluindo a correção para o erro de superposição do conjunto de bases (BSSE). A freqüência para o estiramento da ligação de van der Waals e a freqüência e a intensidade da ...

In the present study, our aim is to investigate the preferential binding mode and encapsulation of the flavonoid fisetin in the nano-pore of β-cyclodextrin (β-CD) at the molecular level using various theoretical approaches: molecular docking, molecular dynamics (MD) simulations and binding free energy calculations. The molecular docking suggested four possible fisetin orientations in the cavity...