How will the dichlophenyl group affect the geometric structure, electronic properties, and static linear polarizability of La@C72?

The generally gradient approximation based on density functional theory is used to find out what effects are brought by the dichlophenyl group on the La@C-72 molecule. It is found that the most stable isomer of La@C-72 is formed by placing the La atom into the C-2 symmetric C-72 cage. The most favorable endohedral site of La atom in La@C-72(C-2) is off-center along the C-2 axis in the sigma(h) plane pointing to the [5, 5] bond, the fusion of two pentagons, yielding a structure marked as La@C-72(C-2)-1. It is interesting that five La@C-72(C-2) isomers considered all have 1 mu(B) magnetic moment, while La@C-72(C6H3Cl2) has a closed-shell electronic structure. With respect to the static linear polarizability, La@C-72(C-2)-1 shows a giant anisotropy than that of C-60 because of its lower C-2 symmetric structure in contrast to the isotropic polarizability Of C-60 with I-h symmetric structure, as well as the transference of three valence electrons from La atom to the carbon cage. However, the three components of La@C-72(C6H3Cl2) along the x, y, and z directions are 638.53, 228.86, and 413.22 angstrom(3) with the mean value 426.87 angstrom(3), much larger than those of 77.4 angstrom(3) for C-60 and 363.47 angstrom(3) for La@C-72(C-2)-1. The static linear polarizabily anisotropy of La@C-72(C6H3Cl2), 355.26 angstrom(3), is much larger than that of La@C-72(C-2)-1, 129.18 angstrom(3), because the inclined dichlorophenyl group completely destroys the C-2 symmetry of La@C-72(C-2)-1. (C) 2008 Elsevier B.V. All rights reserved.