A broad diverse test set of alkanes and cycloalkanes previously studied with MM4 calculations has had the heats of formation calculated by several different quantum mechanical methods: HartreeFock, MP2, and MP4, and also by B3LYP and B3LYP + dispersion energy. Overall, three computational methods (MM4, MP4, and B3LYP + dispersion) yield results that are generally of experimental accuracy. These...

We have computed the energies of adsorption of molecular hydrogen on a number of molecular linkers in metal–organic framework solid materials using density functional theory (DFT) and ab initio molecular orbital methods. We fi nd that the hybrid B3LYP (Becke three-parameter Lee–Yang–Parr) DFT method gives a qualitatively incorrect prediction of the hydrogen binding with benzenoid molecular link...

The frozen domain effective fragment molecular orbital method is extended to allow for the treatment of a single fragment at the MP2 level of theory. The approach is applied to the conversion of chorismate to prephenate by Chorismate Mutase, where the substrate is treated at the MP2 level of theory while the rest of the system is treated at the RHF level. MP2 geometry optimization is found to l...

Detailed investigation of the tautomerism of oxazolidines, thiazolidines and selenazolidines substituted at positions 2 and 4 by hydroxy and amino groups was carried out by calculations at HF and MP2 levels of theory and NMR spectroscopy. The relative stabilities of the tautomers of the heterocycles were calculated in gas phase and in solvents CHCl3 and DMSO utilizing the PCM method. The ab ini...

Asymmetric cell divisions play a key role in establishing neuronal diversity in the mammalian and Drosophila CNS, but the mechanisms involved are mostly unknown. The Drosophila MP2 precursor divides asymmetrically to generate the dMP2/vMP2 interneurons. Delta-Notch signaling is required to specify vMP2 fate, whereas the localized determinant Numb is segregated into dMP2 and is required to speci...

The kinetics for the previously proposed 114-reaction mechanism for the chemical vapor deposition (CVD) process that leads from methyltrichlorosilane (MTS) to silicon carbide (SiC) are examined. Among the 114 reactions, 41 are predicted to proceed with no intervening barrier. For the remaining 73 reactions, transition states and their corresponding barrier heights have been explored using secon...

We present a novel method that appropriately handles both dynamical and static electron correlations in a balanced manner, using a perturbation theory on a spin-extended Hartree-Fock (EHF) wave function reference. While EHF is a suitable candidate for degenerate systems where static correlation is ubiquitous, it is known that most of dynamical correlation is neglected in EHF. In this work, we d...

The Gaussian-type orbital and Gaussian-type geminal (GGn) model is applied to the water molecule, at the level of second-order Møller-Plesset (MP2) theory. In GGn theory, correlation factors are attached to all doubly-occupied orbital pairs (GG0), to all doubly-occupied and singly-excited pairs (GG1), or to all orbital pairs (GG2). Optimizing the GG2 model using a weak-orthogonality functional,...