Accurate MP2 and CCSD(T) complete basis set (CBS) interaction energy curves (14 points for each curve) have been obtained for 20 of the dimers reported in the S22 set and analytical Morse curves have been fitted that can be used in developing updated density functional theory (DFT) and force field models. The magnitude and the effect of the basis set superposition error (BSSE) were carefully in...

BSSE algorithms  Each keyword is considered as a vector in order to perform inner product during the search phase.  Boolean symmetric searchable encryption BSSE is mainly based on the orthogonalization of the keyword field according to the GramSchmidt process.  Searchable encryption: Searching encrypted keywords using encrypted queries (trapdoor) in order to retrieve encrypted documents with...

Molecules of utmost importance like DNA and RNA nucleobases are predicted to be nonplanar by a typical ab initio method, such as second order Møller-Plesset perturbation theory (MP2) combined with standard Pople's basis sets. Similarly to the case of other planar aromatic systems, these pitfalls can be explained in terms of intramolecular basis set superposition error (BSSE) effects, induced by...

We predict structures and energies of water clusters containing up to 19 waters with X3LYP, an extended hybrid density functional designed to describe noncovalently bound systems as accurately as covalent systems. Our work establishes X3LYP as the most practical ab initio method today for calculating accurate water cluster structures and energies. We compare X3LYP/aug-cc-pVTZ energies to the mo...

Mo/ ller–Plesset ~MP2! and Becke-3-Lee-Yang-Parr ~B3LYP! calculations have been used to compare the geometrical parameters, hydrogen-bonding properties, vibrational frequencies and relative energies for several X and X hydrogen peroxide complexes. The geometries and interaction energies were corrected for the basis set superposition error ~BSSE! in all the complexes ~1–5!, using the full counte...

We describe some details related to a new, general, and efficient implementation of the BSSE-free SCF and second-order Møller-Plesset perturbation theories of intermolecular interactions, based on the "Chemical Hamiltonian Approach" (CHA). The program is applicable for both open-shell and closed-shell systems and for an arbitrary number of interacting subsystems. With the new program the CHA me...

Theoretical calculations have been performed for different possible hydrogen bonding complexes between adenine and hydrogen peroxide (AHP). The studied complexes (1-6) were cyclic ones showing two hydrogen bonds of different strength. All of the structures have been characterized at the B3LYP/6-31G(2d,p) and MP2(full)/6-31G(2d,p) levels, yielding only real frequencies (minima) at the B3LYP/6-31...

to get a mole of a gas, it is necessary to calculate the intermolecular interaction. theseintermolecular interactions can be depicted by drawing the potential energy of a pair molecule inrelation to the distance. the intermolecular potential energy surface in the mixtures of ch4-h2cogases from ab initio calculations has been explored. in ab initio calculations the basis setsuperposition error (...

in this research, this possibility was investigated the relative stablilty geometry and bindingenergies of the hydrogen bonds of molybdate-phosphonic acid (mpa) complex in gas phase onthe basis of result of ab initio and dft calculations. three dft methods have been applied forcalculations are b3lyp, bp86 and b3pw91 that have been studied in two series of basis sets:d95** and 6-31+g(d,p) for hy...

The different configurations (linear, zig-zag, and cyclic) of formamide dimers have been studied at the level of both Hartree–Fock (HF) and second order Møller–Plesset perturbation theory (MP2). The widely used a posteriori Boys–Bernardi “counterpoise” (CP) correction scheme has been compared with our a priori methods utilizing the “chemical Hamiltonian approach” (CHA). The appropriate interact...