Diamagnetic orbital term

After this step one may already identify the paramagnetic and diamagnetic terms as arising from the pp and pn first order orbital corrections to the zeroth order wave function. The contribution is then further approximated by neglecting all off-diagonal terms in the pn-pn part of the Hessian... 

The s electrons may be considered as free electrons. In such case, the orbital diamagnetism is the Landau term... 

The first term represents the modification to the spin-other-orbit coupling by the external field, the second term is the corresponding modification of the orbit orbit coupling, and the third term represents the electronic contribution to the diamagnetism. As with the original orbit-orbit coupling term, the second term in (3.172) is incorrect since it does not take account of the retardation effects. The correct form of this term is actually... 

If the material is paramagnetic xm positive), the small negative diamagnetic term NqpL( can be neglected in Eq. (7) and the constant C can be determined. The atomic moment ft can then be calculated from Eq. (9). With neglect of any orbital contribution, the number of unpaired electrons can be found approximately with Eq. (4). Calculate the number of unpaired electrons for each paramagnetic substance studied. 

The derivation of the nuclear magnetic parameters, i.e. , 82 and k(2 ° is similar to the case of the electron magnetic parameters. The magnetic susceptibility tensor is identical with the derivation done before and, in the absence of electron spin (spin-orbit interaction), only the diamagnetic term survives. 

The second-order contribution of the orbital Zeeman term with itself produces a term in the effective Hamiltonian which is quadratic in 5. It therefore has the same form as the diamagnetic susceptibility contribution to the energy it provides the paramagnetic or high-frequency contribution to the susceptibility of the molecular system. The resultant term in the effective Zeeman Hamiltonian is... 

These two terms are known as the paramagnetic and diamagnetic terms, respectively and / is a molecular orbital in the presence of the magnetic field, p is the classical linear momentum operator and A the vector potential. In the so-called CSGT or CTOCD-DZ or ipsocentric methods [79-82], the second term is effectively put to zero via the special choice of gauge. What ranains eventually, is the paramagnetic term ... 

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