Relative stabilities of the fullerenic structures C60, Si60, and Ge60are studied by means of semiempirical quantum-chemical methods. It is suggested that atomization energies rather than heats of formation should be used for the purpose at this level of description. In the former terms Si60and Ge60are located higher than the fullerene itself by about 4100 and 6500 kcal/mol, respectively. A poor SCF convergence is reported for both fullerene analogues. While Si60still exhibits the exactIhsymmetry, the Ge60cage shows some distortion from the highly symmetric form though the fullerenic topology is present. Mass effects create a considerably narrow vibrational spectrum for Si60and especially Ge60. A related computation on B60suggests a better energy position comparing to Si60.
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