Slides

QM/MM: Production
• Controlling adiaba4city for CP dynamics in pra4ce
– Adiaba4city:
separa4on of ionic and electronic degrees of freedom
• separa4ng the power spectrum of the orbital classical fields from the phonon
spectrum of the ions, i.e. the gap between the lowest electronic frequency and
the highest ionic frequency should be large enough
• electronic frequencies depend on the fic44ous electron mass (EMASS), which
can be op4mized to rise the lowest frequency appropriately (might turn out to
be difficult in prac4ce).
• Control: test simula4ons with observa4on of the energy components
• EKINC: should be monitored
– the fic44ous kine4c energy of the electrons might have a tendency to grow.
– a‚er an ini4al transfer of a lible kine4c energy, the electrons should be much colder
than the ions, since only the will the electronic structure be close to the Born-­‐
Oppenheimer surface and thus, the wave func4on and forces derived from it are
meaningful.
• Ensuring adiaba4city of CP dynamics consists of decoupling the two subsystems
and thus minimizing the energy transfer between ionic and electronic degrees of
freedom.
• In this sense CP dynamics is kept in a metastable state.