Cheng-Lin Luo

Theoretical study of magnetostructural correlations in a family of triangular manganese(III) complexes.

A theoretical density functional study of the magnetostructural correlations in a family of triangular [Mn(3)O](7+) systems is presented. Our calculations show that to obtain a good [Mn(3)O](7+) system with strong Mn-Mn ferromagnetic interactions and a large negative D value, we can first decrease tau formed by the two planes of Mn(1)NO(2-) and Mn(2)OO(2-) through changing the orientations of the terminal ligands involving mu-NO exchange pathways (this operation will weaken the Mn-Mn ferromagnetic interactions) to obtain a large negative D value, and then increase tau through distorting Mn-N-O-Mn angles and/or enlarge d (the deviation of the mu(3)-O(2-) ion from the [Mn(III)(3)] plane) to enhance the Mn-Mn ferromagnetic interactions.

Magnetostructural correlations in the cyano-bridged CrNi, Cr2Ni and CrNi6 complexes: density functional theory calculations

A theoretical density functional study of the magneto-structural correlations in a series of the cyano-bridged CrnNim systems is presented. Two approaches with several LDA and GGA functionals gave the result that the ferromagnetic coupling interactions between the nearest-neighbors CrNi weaken with the increase of the number of exchange interactions and the decrease of the Ni–Nbrid–Cbrid angles. Moreover, Kahns qualitative theory succeeded in being applied to interpret the relationships J ≈ n (the number of exchange interactions) and J ≈ θ (the Ni–Nbrid–Cbrid angle) through the overlap integral Sij and the spin density populations on Cr(III) and Ni(II).

Exchange coupling and magnetic anisotropy in a family of bipyrimidyl radical‐bridged dilanthanide complexes: Density functional theory and ab initio calculations

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.

Exploring the sources of the magnetic anisotropy in a family of cyanide-bridged Ni9Mo6 and Ni9W6 systems: a density functional theory study.

A density functional theory (DFT) study of the magnetic coupling interactions and magnetic anisotropy in a family of experimentally synthesized Ni(9)Mo(V) and Ni(9)W(V) systems is presented. Our calculations show that for all of our selected Ni(9)M(6) systems, the intramolecular magnetic coupling interactions are ferromagnetic, and the ground-state spins are 12. All of the D values of Ni(9)W(6) systems come mainly from the contribution of the D(i) of W(6)(CN)(48)Ni extracted from Ni(9)W(6), and the influence of the eight surrounding Ni including the ligands on their magnetic anisotropy is very small. Although the surrounding Ni bounded by different ligands have a small influence on all D values for our selected complexes, they decide on the core structures of W(6)(CN)(48)Ni, which dominate their magnetic anisotropy. Thus, to obtain a Ni(9)W(6) system having a large negative D, we can use different ligands bound to Ni to obtain a good core structure of W(6)(CN)(48)Ni with a large negative D value. All D values of Ni(9)Mo(6) systems also come mainly from the contribution of D(i) of the Mo(6)(CN)(48)Ni, which is positive or negative but very small; most of these systems do not behave as single-molecule magnets.

A possible formation mechanism of double-walled and multi-walled carbon nanotube: a molecular dynamics study

Molecular dynamics simulations based on an empirical potential were performed to study the interaction of graphene nanoribbons and the single-walled carbon nanotubes. The results indicated that a piece of graphene nanoribbon can form a tube structure inside or outside single-walled carbon nanotubes spontaneously under certain condition. Based on this kind of spontaneous phenomenon, we proposed a new possible formation mechanism of double walled carbon nanotube and multi-walled carbon nanotube, and suggested the possibility of controlling the structure of double-walled carbon nanotube and/or multi-walled carbon nanotube.