Geometry optimization in generalized natural internal coordinates

Abstract

The automatic generation of natural internal coordinates is extended to all cases except multiply fused ring systems, i.e., “cages.” This is achieved by a relatively simple code; most of the geometrical cases can now be treated by a single subroutine. To handle molecules containing cages we combine the natural internal coordinates with the delocalized coordinates of Baker, Kessi, and Delley. We have also modified the delocalized coordinates to separate modes with strongly different force constants. The new methods show very good convergence properties in geometry optimizations. Our test set of molecules covers a wide range of atoms and of different bonding situations. For such molecules good internal coordinates are particularly important because no reliable initial force constant matrix can be obtained to accelerate convergence.

Ligand field strengths of carbon monoxide and cyanide in octahedral coordination

“…Each calculation assumed octahedral symmetry and was performed with an m3 gridsize [16]. The geometry of each complex was optimized using TURBOMOLE's JOBEX program with generalized internal coordinates [17]. The energies of the molecular orbitals in the ground state were then calculated with the DSCF module for semi-direct self-consistent field evaluation.…”

Synthesis, Coordination Chemistry and Bonding of Strong N‐Donor Ligands Incorporating the 1H‐Pyridin‐(2E)‐Ylidene (PYE) Motif

“…The geometries of 1 and 11 were optimised at the PBE0/TZVPP level by using TURBOMOLE (using the updated def2-TZVPP basis set), and the stationary points were confirmed as minima by vibrational frequency analyses. [58][59][60][61] Calculated and experimental bond lengths of PYE and protonated derivatives are compared in Table 3. The geometrical parameters of the optimised structures of 1 and 11 compare well with the X-ray crystal structures of 9 and 11, respectively, given that some differences are expected between the solid-state and gas-phase structures as well as the necessity to use experimental data from 9 because the structure of 1 was unavailable.…”

Methanaktivierung durch (Al2O3)x+ (x=3,4,5): die Rolle von Sauerstoff‐zentrierten Radikalen bei thermischer Abstraktion eines Wasserstoffatoms von Methan

“…Anschließend wurden Al n O m + -Cluster massenselektiert, und die Reaktivitätsstudi-en wurden bei einem Methandruck von 9 10 À8 mbar durchgeführt. Die Berechnungen wurden mit der Hybrid-Dichtefunktionalmethode B3LYP [27] unter Verwendung von Triple-z-Basissätzen mit Polarisationsfunktionen (TZVP) [28] und Turbomole 5.7 [29] ausgeführt. Korrekturen der Nullpunktenergie wurden mithilfe der harmonischen Annäherung, basierend auf der analytischen Ableitung der Energie hinsichtlich der Kernkoordinaten, berechnet.…”