Automated generation of coupled-cluster diagrams: implementation in the multireference state-specific coupled-cluster approach with the complete-active-space reference

An algorithm for generation of the spin-orbital diagrammatic representation, the corresponding algebraical formulas, and the computer code of the coupled-cluster (CC) method with an arbitrary level of the electronic excitations has been developed. The method was implemented in the general case as well as for specific application in the state-specific multireference coupled-cluster theory (SSMRCC) based on the concept of a "formal reference state." The algorithm was tested in SSMRCC calculations describing dissociation of a single bond and in calculations describing simultaneous dissociation of two single bonds--the problem requiring up to six-particle excitations in the CC operator.     

Isotope effects in dipole-bound anions of acetone

Precision measurements using the Rydberg charge-exchange and electric field-detachment methods find that the dipole-bound electron affinity (EA) of acetone (C3H6O) is 55+/-10 mueV greater than for deuterated acetone (C3D6O). The result agrees well with a theoretical prediction obtained with high-level electronic-structure and anharmonic vibrational calculations. The dipole moments calculated for the vibrationally averaged structures of C3H6O and C3D6O show that the isotope effect (2% reduction) on the EA of acetone is mainly due to a slight reduction (0.5%) of the average dipole moment upon deuteration.     

Catalytic Preparation of Non-Symmetrical Ketones in the Gas Phase Over Iron Oxide

The catalytic conversion of esters and mixtures of alcohols and aldehydes in the gas phase over iron oxide has been studied. The method allows for effective synthesis of non-symmetrical ketones.     

Einige Bemerkungen zur Struktur des Kohlensuboxidpolymeren

Zusammenfassung Das Quarz-Ultraviolettspektrum und das Infrarotspektrum des Polymeren (C₃O₂) _n das man bei Zimmertemperatur in geringer Konzentration durch Blockpolymerisation erhalten hat, wurde untersucht. Im Infrarotspektrum stellte man fest, daß eine Gruppe C=O im Polymeren vorhanden ist. Außerdem bemerkte man eine Absorption des in Chloroform gelösten Polymeren um 255 und 308 nm; sie wird als Übergang der CO-Gruppe durch deren Aufspaltung infolge einer Schwingungskopplung in der Struktur des Dimertyps des Kohlensuboxidpolymeren (C₃O₂) _n interpretiert. So können wir eine Dimerstruktur für das Polymer (C₃O₂) _n , das wir bei niedrigen Temperaturen gewonnen haben, vorschlagen. Weiters wird der Übergang dieser Struktur in die vonBlake diskutiert.

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The UV and IR spectra of (C₃O₂) _n polymer were investigated. The (C₃O₂) _n polymer was obtained from C₃O₂ by block-polymerization at room temperature in small concentrations. The UV spectrum of the polymer in CHCl₃ has maxima at 255 nm and 308 nm. These two bands are interpreted by the vibronic splitting of the n—*·transition of groups in the dimer. A dimeric structure of the (C₃O₂) _n polymer obtained at room temperature is postulated. The transition between dimeric andBlake's structure is discussed.

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Mit 2 Abbildungen     

Gaussian geminal basis set optimization with crude SCF reference state

Gaussian geminal basis functions for second-order correlation energy calculations according to the Sinanogˇlu method are optimized with reference to rather crude SCF functions. The optimized geminal basis set is then used in a one-step calculation of the correlation energy with respect to the near-Hartree-Fock reference State. The numerical results for the beryllium atom indicate the usefulness of the proposed technique.     

Non-Born-Oppenheimer study of positronic molecular systems: e(+)LiH

Very accurate non-Born-Oppenheimer variational calculations of the ground state of e(+)LiH have been performed using explicitly correlated Gaussian functions with preexponential factors dependent on powers of the internuclear distance. In order to determine the positron detachment energy of e(+)LiH and the dissociation energy corresponding to the e(+)LiH fragmentation into HPs and Li(+) we also calculated non-BO energies of HPs, LiH, and Li(+). For all the systems the calculations provided the lowest ever-reported variational upper-bounds to the ground state energies. Annihilation rates of HPs and e(+)LiH were also computed. The dissociation energy of e(+)LiH into HPs and Li(+) was determined to be 0.036 548 hartree.     

A(SLq(2)) at Roots of Unity is a Free Module over A(SL(2))

It is shown that when q is a primitive root of unity of order not equal to 2 mod 4, A(SL_q(2)) is a free module of finite rank over the coordinate ring of the classical group SL(2). An explicit set of generators is provided.     

Exponentially and pre-exponentially correlated Gaussians for atomic quantum calculations

Explicitly correlated, n-electron, one-center s Gaussian (ECG) functions that depend on the interelectron distances in the exponent are combined with s ECGs which also depend on the interelectron separations through pre-exponential r(ij)(2) multipliers. The pre-exponentially r(ij)(2)-dependent ECGs are included in the basis to better describe the interelectron correlation and the interelectron cusps. The basis set is tested in the calculations of the ground state of the beryllium atom ((9)Be).