Hyperfine coupling constants for

Compute the isotropic hyperfine coupling constant for each of the atoms in HNCN with the HF, MP2, MP4(SDQ) and QCISD methods, using the D95(d,p) basis set Make sure that the population analysis for each job uses the proper electron density by including the Density=Current keyword in the route section. Also, include the 5D keyword in each job s route sectionfas was done in the original study). 

Table 18.2 Hyperfine coupling constant for a hydrogen atom when the Is orbital is represented as an uncontracted sum of n primitives...

Spectra of radicals in a dilute single crystal are obtained for various orientations, usually with the field perpendicular to one of the crystal axes. Each spectrum usually can be analyzed as if they were isotropic to obtain an effective g-value and hyperfine coupling constants for that orientation. Since the g- and hyperfine-matrix principal axes are not necessarily the same as the crystal axes, the matrices, written in the crystal axis system, usually will have off-diagonal elements. Thus, for example, if spectra are obtained for various orientations in the crystal vy-plane, the effective g-value is ... 

The tin hyperfine coupling constants for the hexaphenylditin radical anion enable values for the occupancy of the unpaired electron in the tin 5s and 5p orbitals of 0.10 and 0.34, respectively, to be calculated. This would imply that the electron occupies a tin sp3 hybrid orbital. Since the radical contains two tin atoms, the total spin density residing with the tin centres is ca 0.9. There is very little spin density residing with the ligands, and the... 

S. C. Larsen, DFT calculations of proton hyperfine coupling constants for [V0(H20)5]2+ Comparison with proton ENDOR data, /. Phys. Chem. A, 105 (2001) 8333-8338. 

Copper proteins have been classified according to their spectroscopic properties (Malkin and Malmstrbm, 1970 Fee, 1975) as type I, II, or III. Type I blue copper proteins are characterized by an extraordinarily intense absorption near 600 nm and by unusually small hyperfine coupling constants for the paramagnetic [oxidized Cu(II)] form of the protein. 

Phenylcyclopropane radical cation (9 ) has divergent hyperfine coupling constants for the secondary cyclopropane protons (aptrans = 0.78 mT upcis = 0.07 mT CIDNP, B3LYP/6-31G calculations), apparently because the cis protons are located in a nodal plane. " Similarly, vinylcyclopropane radical cation is... 

Once a description of the electronic structure has been obtained in these terms, it is possible to proceed with the evaluation of spectroscopic properties. Specifically, the hyperfine coupling constants for oligonuclear systems can be calculated through spin projection of site-specific expectation values. A full derivation of the method has been reported recently (105) and a general outline will only be presented here. For the calculation of the hyperfine coupling constants, the total system of IV transition metal centers is viewed as composed of IV subsystems, each of which is assumed to have definite properties. Here the isotropic hyperfine is considered, but similar considerations apply for the anisotropic hyperfine coupling constants. For the nucleus in subsystem A, it can be... 

In a comment on this work,39 Close expresses doubt regarding the DFT calculations that indicate a lack of planarity in pyrimidine radical anions, contrary to what is experimentally found in low temperature single crystal studies. He notes that using an extended basis set results in reasonable agreement between the experimental and calculated values of hyperfine coupling constant for the a-proton without the need to move the proton significantly out of the... 

Calculate the hyperfine coupling constant for a deuterium atom. 

The low-temperature reduction of these compounds in THF with potassium metal leads to the formation of an anion radical solution yielding a simple ESR spectrum. The remarkable lack of temperature dependence of the hyperfine coupling constants for the entire series of anion radicals, the absence of alkali metal coupling, and the excellent agreement between the calculated and experimental spin densities would seem to indicate the lack of ion pairing in these systems. However, it is most likely that these anion radicals (92) are strongly ion-paired in THF. The fact that... 

Isotropic Proton and 14N Hyperfine Coupling Constants for the Nitrobenzene Anion and some of its Derivatives (G)... 

Proton and 13C Isotropic Hyperfine Coupling Constants for Aliphatic Ketyls (G) (Hirota and Weissman, 1960)... 

Proton Hyperfine Coupling Constants for Certain Aliphatic Radicals... 

Fig. 13. Angular dependence of the isotropic hyperfine coupling constant for the jS-protons in RCH2CR2 radicals. The individual (dashed line) and total (solid line) couplings are shown.

Table 32. Selected ) examples of correlation between experimental and calculated isotropic hyperfine coupling constants for...

Table 37. Calculated and observed isotropic hyperfine coupling constants for methyl radical and isotopically substituted derivatives...

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