LORG

LORG (localized orbital-local origin) technique for removing dependence on the coordinate system when computing NMR chemical shifts LSDA (local spin-density approximation) approximation used in more approximate DFT methods for open-shell systems LSER (linear solvent energy relationships) method for computing solvation energy... 

Hydroxyurea [127-07-1] M 76.1, m 70-72 (unstable form), m 133-136°, 141 (stable form), pK 10.6. Recrystallise from absolute EtOH (lOg in 150mL). Note that the rate of solution in boiling EtOH is slow (15-30 min). It should be stored in a cool dry place but some decomposition could occur after several weeks. lOrg Synth Coll Vol V 645 1973.] It is very soluble in H2O and can be crystd from Et20. [Acta Chem Scand 10 256 1956.]... 

In previous presentations [16-19,28], the LORG equations are formulated in a nucleus centered coordinate system. Explicit reference to a field point R, can be introduced following eq.(13), and the resulting LORG equations for the i, j th element of the shielding tensor become... 

A common origin paramagnetic contribution can subsequently be obtained as the difference between the LORG total shielding tensor and the diamagnetic contribution from eq.(29), i.e. 

As indicated, the possibility of orbital decomposition is retained in the diamagnetic and paramagnetic terms in eqs.(29,30). The value for the paramagnetic shielding contribution extracted via eq.(30) does not, of course, correspond to a well-defined basis set, but is at the same level of numerical quality as the LORG calculation used for the total shielding. 

There are several alternative computational methods for obtaining NMR data such as the GIAO method (Wolinski et al., 1990), the LORG method (Bouman and Hansen, 1989), and IGAIM (Keith and Bader, 1992). 

Recently, ab initio shielding calculations based on well-established theories, IGLO (individual gauge for localized orbitals)9, GIAO (gauge including atomic orbital)10 and LORG... 

In the LORG theory, occupied orbitals are localized according to the Foster-Boys criterion16. In the calculations described above they chose the LORG centroid assignment113. 

By applying polarization functions, ab initio shielding calculations for some polyenals and their Schiff bases reproduce the experimental values well even on the carbonyl and the imine carbons using the LORG theory without including correlation effects. In addition, there is a trend that the calculation with polarization functions yields smaller anisotropies of chemical shieldings than those without polarization functions. 

M., Ishidate, M., Lorge, E. et al. (2000) Report from the in vitro micronudeus assay working group. Environmental and Molecular Mutagenesis, 35, 167-172. 

Such a comprehensive oppraoch towards the process selection has resulted in the development of production facilities which are simple, reliable and efficient thus permitting o very lorge through-put (34 x 10 m /d) to be produced ond processed on a single platform. 

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