Study of orbital transformation in configuration interaction calculations of hyperfine coupling in nitrogen and the CH molecule

Multi-reference configuration interaction calculations employing various orbital transformations are undertaken to obtain the isotropic hyperfine coupling constanta _iso in nitrogen anda _iso(H) in the CH molecule. The natural orbital (NO) basis is found to be more effective than the simple RHF-MO basis; the most obvious is a basis of spin natural orbitals (SNO). It is found thata _iso is approached from opposite sides in the NO and 2s shell SNO basis if the CI expansion is increased. Both results are within a few percent of the full CI limit for the nitrogen atom (in the given AO basis) and the experimental value for H in the CH radical. Various features of the SNO are discussed.     

Debenz[c,j]octalen

Dibenzo[c,j]octalene (2), to be regarded as a model for the hypothetical octalene double bond isomer (1), has been synthesized. As borne out by NMR studies, (2) exists as an equilibrating mixture of the anticipated conformers (2a) and 2(b).     

Polyurethanes: Versatile Materials and Sustainable Problem Solvers for Today’s Challenges

Polyurethanes are the only class of polymers that display thermoplastic, elastomeric, and thermoset behavior depending on their chemical and morphological makeup. In addition to compact polyurethanes, foamed variations in particular are very widespread, and they achieve their targeted properties at very low weights. The simple production of sandwich structures and material composites in a single processing step is a key advantage of polyurethane technology. The requirement of energy and resource efficiency increasingly demands lightweight structures. Polyurethanes can serve this requirement by acting as matrix materials or as flexible adhesives for composites. Polyurethanes are indispensable when it comes to high‐quality decorative coatings or maintaining the value of numerous objects. They are extremely adaptable and sustainable problem solvers for today’s challenges facing our society, all of which impose special demands on materials.     

First Measurements with the Gas Cell for SHIPTRAP

SHIPTRAP is an electromagnetic transport and trapping system to provide very clean and cold beams of singly-charged recoil ions from the SHIP facility at GSI. The different components of the system are currently under development in Munich (gas cell and extraction RFQ) and GSI (Buncher RFQ and Penning traps)[1]. Design and manufacturing of the prototype buffer gas cell and the extraction RFQ based on a wide range of simulations have been completed. The results of these simulations together with the first measurements will be reported. This revised version was published online in July 2006 with corrections to the Cover Date.     

Boranediyl- and Diborane(4)-1,2-diyl-Bridged Platinum A-Frame Complexes

Diplatinum A-frame complexes with a bridging (di)boron unit in the apex position were synthesized in a single step by the double oxidative addition of dihalo(di)borane precursors at a bis(diphosphine)-bridged Pt⁰₂ complex. While structurally analogous to well-known μ-borylene complexes, in which delocalized dative three-center-two-electron M-B-M bonding prevails, theoretical investigations into the nature of Pt−B bonding in these A-frame complexes show them to be rare dimetalla(di)boranes displaying two electron-sharing Pt−B σ-bonds. This is experimentally reflected in the low kinetic stability of these compounds, which are prone to loss of the (di)boron bridgehead unit.     

DIESEL-MP2: a new program to perform large-scale multireference-MP2 computations

This article presents a new MR‐MP2 code (Multi‐Reference Møller–Plesset 2nd order) suitable for the computation MR‐MP2 energies of extended systems with strong near degeneracy effects (e.g., open shell systems). It is based on the DIESEL program package developed by Hanrath and Engels. Due to improved algorithms the new code is able to handle systems with 400–500 basis functions and more than 100 electrons. The code is made for parallel computers with distributed memory, but can also be run on local machines. It possesses two integral interfaces (MOLCAS, TURBOMOLE). The algorithms are briefly introduced and timings for the Neocarzinostatin chromophore are presented. The efficiencies of the codes obtained with Intel or GNU compilers are compared. © 2006 Wiley Periodicals, Inc. J Comput Chem 27: 1055–1062, 2006