The chiral self-discrimination of twelve molecules showing axial chirality has been studied. They included peroxides, hydrazines, carboxylic acids, amides, and allenes. The homo and heterochiral dimers of the selected compounds, that present two hydrogen bonds, have been studied by means of density functional theory ~B3LYP/6-311G**! and ab initio ~MP2/6-311G** and MP2/6-31111G**! methods. The e...

A satisfactory account of the van der Waals (vdW) (London dispersion) forces is, in general not possible by the Kohn-Sham method using standard local, semilocal generalized gradient approximation (GGA), or meta-GGA density functionals. The recently proposed range-separated hybrid (RSH) approach, supplemented by second order perturbational corrections (MP2) to include long-range dynamic correlat...

The development of Møller–Plesset perturbation theory (MPPT) has seen four different periods in almost 80 years. In the first 40 years (period 1), MPPT was largely ignored because the focus of quantum chemists was on variational methods. After the development of many-body perturbation theory by theoretical physicists in the 1950s and 1960s, a second 20-year long period started, during which MPn...

The results of harmonic and anharmonic frequency calculations on a guanine-cytosine complex with an enolic structure (a tautomeric form with cytosine in the enol form and with a hydrogen at the 7-position on guanine) are presented and compared to gas-phase IR-UV double resonance spectral data. Harmonic frequencies were obtained at the RI-MP2/cc-pVDZ, RI-MP2/TZVPP, and semiempirical PM3 levels o...

We present a computationally efficient implementation of double-hybrid density functional theory (DH-DFT) leveraging the dual basis methods Head-Gordon and co-workers resolution-of-the-identity second-order Møller-Plesset (RI-MP2) theory. The B2PLYP, B2GP-PLYP, DSD-BLYP DSD-PBEP86 functionals are applied to assess performance dual-basis on several benchmark test cases, including CONF set confor...

The optimized geometry and energy for [K(H2O)n=1-8] clusters have been studied using different basis sets and different methods (HF, MP2(FULL), BLYP and B3LYP). Moreover, two analytical potentials have been developed for potassium in water based on MP2(FULL) and B3LYP computations using the 6311g* for potassium and the aug-cc-pVTZ(H2O) basis set for water. Two molecular dynamics simulations hav...

the armaticity of 5 methylcytosine tautomers in the gas phase has been studied and the chemical structures of related tautomers are investigated . the electronic energy, enthalpy and free energy of each tautomer are also estimated at the b3lyp/6-31 g* // b3lyp/6-31 g* and mp2 / 6-31 g* // mp2 / 6-31 g* levels

The solvation of alanine is investigated, with a focus on adding a sufficient number of discrete water molecules to determine the first solvation shell for both the nonionized (N) and zwitterionic (Z) forms to converge the enthalpy of solvation and the enthalpy difference for the two forms of alanine. Monte Carlo sampling was employed using the generalized effective fragment potential (EFP) met...