TY  - JOUR
A1  - Kaupp, Martin
A1  - Schleyer, P. v. R.
A1  - Stoll, H.
A1  - Preuss, H.
T1  - Pseudopotential Approaches to Ca, Sr and Ba Hybrides. Why are some Alkaline Earth MX\(_2\) Compounds Bent?
N2  - Quasirelativistic and nonrelativistic lo-valence-electronp seudopotentialsf or Ca, Sr, and Ba are presented. Results of calculations with 6s6p5d basis sets for MH, MH\(^+\) , and MH\(_2\), are compared with all-electron and 2-valence-electron pseudopotential calculations with and , without core-polarization potentials. The lo-valence-electron pseudopotential approach agrees well with all-electron calculations. It circumvents problems for the 2-valence-electron pseudopotentials arising from an incomplete separation of valence and subvalence shells in polar molecular systems due to strongly contracted occupied (n - 1 )-d orbitals. All higherlevel calculations show SrH\(_2\) and BaII\(_2\), to be bent with angles of - 140° and 120°, respectively, while CaH\(_2\) is linear with a flat potential-energy surface for the bending motion. The use of a core-polarization potential together with the 2-valence-electronp seudopotentiala pproach allows an investigation of the relative importance of core-polarization vs direct d-orbital bonding participation as reasons for the bent structures. The calculations strongly suggest that both contribute to the bending in SrH\(_2\) and BaII\(_2\). Even at the Hartree-Fock level of theory lovalence- electronp seudopotentialc alculations given reasonablea nglesw hen the potentialenergy surface is not exceedingly flat, and only moderately contracted basis sets including both compact d functions and diffuse p functions are used. The effect of core-valence correlation and the importance off functions also are discussed.
KW  - Chemie
Y1  - 1991
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31646
ER  - 
TY  - JOUR
A1  - Kaupp, Martin
A1  - Schleyer, Paul. von Rague
A1  - Stoll, Hermann
A1  - Preuss, Heinzwerner
T1  - The Question of bending of the Alkaline Earth Dihalides MX\(_2\) (M = Be, Mg, Ca, Sr, Ba; X = F, C1, Br, I). An ab Initio Pseudopotential Study
N2  - No abstract available
KW  - Anorganische Chemie
Y1  - 1991
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-60166
ER  - 
TY  - JOUR
A1  - Kaupp, Martin
A1  - Stoll, Hermann
A1  - Preuss, Heinzwerner
A1  - Kaim, Wolfgang
A1  - Stahl, Thomas
A1  - van Koten, Gerard
A1  - Wissing, Elmo
A1  - Smeets, Wilberth J. J.
A1  - Spek, Anthony L.
T1  - Theoretical and Experimential Study of Diamagnetic and Paramagnetic Products from Thermal and Light-Induced Alkyl Transfer between Zinc or Magnesium Dialkyls and 1,4-Diaza-1,3-butadiene Substrates
N2  - No abstract available
KW  - Anorganische Chemie
Y1  - 1991
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-60173
ER  -