[1] Univ Insubria, Ctr Nonlinear & Complex Syst, Dipartimento Sci & Alta Tecnol, via Valleggio 11, I-22100 Como, Italy
[2] Ist Nazl Fis Nucl, Sez Milano, via Celoria 16, I-20133 Milan, Italy
[3] Univ Calif Davis, Dept Chem, One Shields Ave, Davis, CA 95616 USA
[4] Ist Sistemi Complessi, Consiglio Nazl Ric, via Madonna del piano 10, I-50019 Sesto Fiorentino, Italy
[5] Univ Firenze, Dipartimento Fis & Astron, Via G Sansone 1, I-50019 Sesto Fiorentino, Italy
[6] INFN Sez Firenze, Via G Sansone 1, I-50019 Sesto Fiorentino, Italy