Résumé
In the present work we generalize Landau theory of crystallization to explain and to classify the capsid structures of small viruses with spherical topology and icosahedral symmetry. We develop an explicit method which predicts the positions of centers of mass for the proteins constituting viral capsid shell. The peculiarities of the assembly thermodynamics are also discussed. Finally, we show the relation between the protein density distributions obtained and the infectivity properties of several human viruses.