The performances of Møller-Plesset second-order perturbation theory (MP2) and density functional theory (DFT) have been assessed for the purposes of investigating the interaction between stannylenes and aromatic molecules. The complexes between SnX2 (where X = H, F, Cl, Br, and I) and benzene or pyridine are considered. Structural and energetic properties of such complexes are calculated using ...

Hydrogen-bonded nucleic acids base pairs substantially contribute to the structure and stability of nucleic acids. The study presents reference ab initio structures and interaction energies of selected base pairs with binding energies ranging from -5 to -47 kcal/mol. The molecular structures are obtained using the RI-MP2 (resolution of identity MP2) method with extended cc-pVTZ basis set of ato...

Local coupled cluster theory is based on (i) a restriction of the list of pairs (or triples) of occupied molecular orbitals, and (ii) a truncation of the virtual space to orbital pair (or triple) specific subspaces. The latter is motivated by an exponential decay of the contributions to the pair energy with respect to the distance between related local occupied and virtual orbitals; the former ...

In this paper, we report the stability of the Li(HF) 3 molecular anion calculated at the MP2/631++G** and CCSD(T)/6-31++G** level of theory. Five possible conformers of Li(HF) 3 molecular anions have been determined employing ab initio MP2 method with 6-31++G** basis set. The most stable conformer of five Li(HF) 3 anions is in a cyclic ring structure Li(HF) 3 (1). From our calculations we show ...

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 (...

The second-order Møller-Plesset perturbation energy (MP2) and the Random Phase Approximation (RPA) correlation energy are increasingly popular post-Kohn-Sham correlation methods. Here, a novel algorithm based on a hybrid Gaussian and Plane Waves (GPW) approach with the resolution-of-identity (RI) approximation is developed for MP2, scaled opposite-spin MP2 (SOS-MP2), and direct-RPA (dRPA) corre...

Counterpoise (CP) corrected optimizations of water dimer using the D95++(d,p) basis set at various levels of MP and DFT are presented. The MP2(full) calculations predict an interaction energy of -4.75 kcal/mol, close to the “MP2 limit” and to reported MP2 calculations with much large basis sets. DFT (B3PLYP) CPcorrected optimization provided the best interaction energy (-5.22 kcal/mol). The opt...

Three major conformations of H(2)S-benzene dimer have been located with a variety of density functional theories (DFT) and second order Møller-Plesset perturbation (MP2). In line with an experiment, MP2 results indicate that the tilted C(s)-symmetry structure is a stable dimer, yet a C(2v)-symmetry structure is only a second-order saddle point. Although all of the examined DFT methods also pred...

Intracellular and extracellular recordings have been made from neurones of the swimmeret system in the semi-isolated abdominal ganglion of the crayfish during rhythmic activity. Extracellular recordings commonly reveal a motor programme (MP1) consisting of low-amplitude symmetrical power and return stroke activity with phase-constant posterior-to-anterior intersegmental coordination. Occasional...

The structures of a number of fluorocarbocations were calculated at the correlated MP2/6-31G* level. 13C and 19F NMR chemical shifts of fluorocarbocations were calculated for the first time using IGLO and GIAO-MP2 methods. The data showed good correlation of calculated 19F and 13C NMR chemical shifts with the experimental chemical shifts of fluorocarbocations. The correlation for GIAO-MP2-calcu...