The usual building blocks of molecular orbital theory are one-center atomic orbitals. If we instead use two-center orbitals derived from the exact solution for H2 , a simple calculation of the H2 binding energy yields 4.5 eV, with a Hylleraas correlation factor having no adjustable parameters. Variational minimization with respect to a couple of parameters in our trial function then shifts the ...

We present a preliminary version of a software package, CHEM1D, that performs molecular orbital calculations on onedimensional atoms and molecules using the unadorned Coulomb operator 1/|x1 − x2|. We describe methods for computing the necessary oneand two-electron integrals and outline the overall structure of the package. We use CHEM1D to perform calculations on a set of small molecules and sh...

correlations between carcinogenicity and several molecular orbital characteristics were found. All correlations between molecular orbital properties and carcinogenicity were modified by one or more of the following structural factors: (a) the absence of a 4-nitro group, (b) the absence of a 1-oxide group, or (c) the presence of bulky substituents in position 2 or 3 of the quinoline ring. Any of...

Orbital energies in Kohn-Sham density functional theory (DFT) are investigated, paying attention to the role of the integer discontinuity in the exact exchange-correlation potential. A series of closed-shell molecules are considered, comprising some that vertically bind an excess electron and others that do not. High-level ab initio electron densities are used to calculate accurate orbital ener...

   In this study the adsorption of selenium molecule (Se2) on the outer surface of zigzag (5,0), (8,0) and (10,0) carbon nanotubes has been investigated. We examined number adsorbed orientations as well as different adsorption sites on nanotubes. The adsorption energies, equilibrium distances, energy differences between the highest occupied molecular orbital (HOMO) and lowest uno...

Ab initio and DFT molecular orbital calculations predict that acetyl radical reacts with acetylene through interactions primarily involving the SOMO of the radical and the in-plane π-bond of acetylene. An energy barrier (∆E1) of 39.6 kJ mol‒1 is predicted for the preferred anti arrangement of reactants at the CCSD(T)/cc-pVDZ//BHandHLYP/cc-pVDZ level of theory. NBO analysis reveals additional in...