Browsing by Author "Rychlewski, Jacek"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item The ground state of (He-H-He)(+) from correlated ab initio calculations(POLISH CHEMICAL SOCIETY, 1998-07) Komasa, Jacek; Rychlewski, JacekHe2H+ ion in its ground state is studied by means of ab initio methods taking into account the electron correlation. Geometry optimization at the CCSD(T)/cc-pV5Z level of theory has been performed and the potential energy hypersurface scan is presented. The optimum conformation is linear and symmetric with the proton at the He-He midpoint and the He-H distance equal to 1.75 bohr. Stabilization energy with respect to the He2H+ --> HeH+ + He dissociation channel has been computed. Additionally, a single point variational calculations with the use of the Exponentially Correlated Gaussian wave functions have been performed. They supply an upper bound to both the total electronic energy (-5.903505 hartree) and the stabilization energy (-13.224 kcal/mol). A comparison of the results from both the perturbational coupled cluster and variational methods is presented.Item THE NUCLEAR MAGNETIC SHIELDING AND SPIN-ROTATION CONSTANTS OF THE HYDROGEN MOLECULE(Elsevier, 1995-04-07) Komasa, Jacek; Rychlewski, Jacek; Raynes, William T.The variation-perturbation method, employing an explicitly correlated basis set in the form of Gaussian functions with exponential correlation factors, has been used to calculate the paramagnetic component of the nuclear magnetic shielding and the electronic contribution to the spin-rotation constant for the hydrogen molecule in its ground state. The diamagnetic components of the shielding tensor have also been computed. The computations have been performed for three internuclear distances in the vicinity of equilibrium. A comparison of the calculated quantities, which are of high accuracy, with the experimental data reveals a small but significant discrepancy between theory and experiment.