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An update to the computational framework CONDON, introducing the ability to model and predict the magnetic and electronic properties of polynuclear exchanged‐coupled actinide systems, such as homonuclear and heteronuclear coordination clusters of 5f ions, is presented. The program can intuitively fit experimental magnetic and spectroscopic data from multiple sources simultaneously, under consideration of a "full model" ligand field theory Hamiltonian. CONDON accounts simultaneously for all aspects relevant to the magnetic characteristics: interelectronic repulsion, ligand field potential, spin‐orbit coupling, interatomic exchange interactions, and applied magnetic field. As exemplified by several examples, CONDON represents the first program package able to accurately describe single‐ion effect in exchange‐coupled actinide systems, limited only by available computational resources. © 2018 Wiley Periodicals, Inc. The magnetochemical computation framework CONDON has been updated to provide comprehensive analysis of the magnetic characteristics of homopolynuclear and heteropolynuclear exchange‐coupled actinide systems. Implementing both effective and "full" models, CONDON offers simulation and fitting methods, the latter simultaneously for different experimental datasets. [ABSTRACT FROM AUTHOR]

Common trends in communication through molecular bridges are ubiquitous in chemistry, such as the frequently observed exponential decay of conductance/electron transport and of exchange spin coupling with increasing bridge length, or the increased communication through a bridge upon closing a diarylethene photoswitch. For antiferromagnetically coupled diradicals in which two equivalent spin centers are connected by a closed-shell bridge, the molecular orbitals (MOs) whose energy splitting dominates the coupling strength are similar in shape to the MOs of the dithiolated bridges, which in turn can be used to rationalize conductance. Therefore, it appears reasonable to expect the observed common property trends to result from common orbital trends. We illustrate based on a set of model compounds that this assumption is not true, and that common property trends result from either different pairs of orbitals being involved, or from orbital energies not being the dominant contribution to property trends. For substituent effects, an effective modification of the π system can make a comparison difficult. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The origin of the magnetic anisotropy energy barriers in a series of bpym− (bpym = 2,2′-bipyrimidine) radical-bridged dilanthanide complexes [(Cp*2Ln)2(μ-bpym)]+ [Cp* = pentamethylcyclopentadienyl; Ln = GdIII ( 1), TbIII ( 2), DyIII ( 3), HoIII ( 4), ErIII ( 5)] has been explored using density functional theory (DFT) and ab initio methods. DFT calculations show that the exchange coupling between the two lanthanide ions for each complex is very weak, but the antiferromagnetic Ln-bpym− couplings are strong. Ab initio calculations show that the effective energy barrier of 2 or 3 mainly comes from the contribution of a single TbIII or DyIII fragment, which is only about one third of a single Ln energy barrier. For 4 or 5, however, both of the two HoIII or ErIII fragments contribute to the total energy barrier. Thus, it is insufficient to only increase the magnetic anisotropy energy barrier of a single Ln ion, while enhancing the Ln-bpym− couplings is also very important. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

A new program, PHI, with the ability to calculate the magnetic properties of large spin systems and complex orbitally degenerate systems, such as clusters of d-block and f-block ions, is presented. The program can intuitively fit experimental data from multiple sources, such as magnetic and spectroscopic data, simultaneously. PHI is extensively parallelized and can operate under the symmetric multiprocessing, single process multiple data, or GPU paradigms using a threaded, MPI or GPU model, respectively. For a given problem PHI is been shown to be almost 12 times faster than the well-known program MAGPACK, limited only by available hardware. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Unrestricted density functional theory calculations have been conducted on three diiron(III) synthetic model compounds containing antiferromagnetically coupled high-spin (HS) irons for which crystallographic structures and Raman spectral data are available. Three density functionals have been employed: BPW91, PWC, and BOP. The study compares the effects on optimized geometries and harmonic vibrational frequencies of spin-paired (SP) low-spin, HS, and broken symmetry antiferromagnetically coupled singlet representations of the spin density distribution. The geometries around the diiron centers in the HS and broken symmetry (BS) representations are found to be similar, both markedly different from those arising from the SP representation. Small differences between the HS and BS results are seen in bond lengths, angles, Raman frequencies, and spin densities associated with oxo and peroxo bridges between the irons. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008 [ABSTRACT FROM AUTHOR]