Perhaps you should try some spelling variations:
"random dynamical system" » "quantum dynamical system", "random dynamical systems", "random dynamic systems"
"quantum chemical system" » "quantum mechanical system", "quantum chemistry system", "quantum chemical systems", "quantum biochemical systems"

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (("random dynamical system") OR ("quantum chemical system")).
• Removing quotes may allow a broader search: (( random dynamical system ) or ( quantum chemical system )).
• Adding a wildcard symbol may retrieve word variants: (("random dynamical system") or ("quantum chemical system"))*.