Coupled Hartree–Fock calculations of molecular magnetic properties annihilating the transverse paramagnetic current density

Abstract

The reliability of the continuous transformations of origin of the current density method, which makes the transverse paramagnetic current vanish (CTOCD-PZ), for the prediction of nearly gauge-origin independent molecular magnetic susceptibility and gauge-origin independent nuclear magnetic shielding, is proved on the basis of a fairly large number of calculations. It is shown that, within the computational scheme provided by the coupled Hartree–Fock perturbation theory (CHF), convergence towards the presumed Hartree–Fock limit, for magnetic susceptibility and proton magnetic shielding, is systematically reached using basis sets which are smaller than those required by conventional common origin and CTOCD-DZ techniques. For second-row nuclear magnetic shieldings a variant of the CTOCD-PZ method, which shifts the origin of the current towards the nearest nucleus for points close to nuclei, as suggested originally by Keith and Bader with the CSDGT method [T. A. Keith and R. F. W. Bader, Chem. Phys. Lett. 210, 223 (1993)], gives likewise good results with affordable basis sets.

Ring Currents in Polycyclic Sodium Clusters

“…[26][27][28] In this method, the current density at each point in the molecule is computed by choosing itself as the origin of vector potential, hence the alternative name 'ipsocentric' for the method.…”

“…This method is now also known as the continuous transformation of origin of current density with diamagnetic zero CTOCD-DZ [26][27][28] or ipsocentric method. [29][30][31] These methods may be used to give a direct visualization of the induced current density in polycyclic Naclusters and their analogous linear polyacenes.…”

A simple model for counter-rotating ring currents in [n]circulenes

“…The advantages of the CTOCD-DZ method for current density and the CTOCD-PZ2 (paramagnetic zero) variant for integrated magnetic properties have been well rehearsed in the literature [6,16,19,20]. For planar 3a the r-, p-and total (r + pÞ current densities induced by a unit magnetic field acting along the principal axis are plotted in a plane 1 a 0 above that of the central ring (that is, close to the maximum p density and where current flow is effectively parallel to the molecular plane [21]).…”

Current density maps, magnetizability, and nuclear magnetic shielding tensors of bis-heteropentalenes. II. Furo-furan Isomers

“…The theory of CTOCD methods can be found elsewhere. 1, [15][16][17] The approach based on London orbitals ͑LO͒, 18,19 sometimes referred to as gauge-including atomic orbitals ͑GIAO͒, implemented in the DALTON package, 20 has also been used. The basis sets are again (13s8p4d) for carbon, (13s8p4d1 f ) for oxygen, and (8s3p) for hydrogen, but the Gaussian orbitals include gauge factors à la London.…”

“…The gauge invariant results obtained via the London orbitals, indicated by LO in Table II, are partitioned into diamagnetic, d , and paramagnetic, p , contributions, evaluated with respect to the center of mass. The notation adopted for the various CTOCD estimates [15][16][17][21][22][23][24] is the same as in paper I of this series. 6 The least symmetric molecule, furo͓3,4-b͔furan, has been studied only via the GIAO approach of the DALTON package.…”