Liquid Crystals pt2 Order Parameters

An order parameter answers the question "how ordered" is our system. What are order parameters? How do we define these? calculate these?

[prbprb]

Thank you for this useful lecture. at 10:00 I think you should mention that for random orientations that S_N is zero. I believe this is also the minimum possible value. I would also argue that the limits of integration at 11:40 should be the whole length of the sample.

[舒克倫]

Quite a clear explanation about the order parameter of liquid crystals. As you know, liquid crystals also contain many different single materials, How we make the liquid crystals with a larger order parameter(OP) through every single material with a different crystal system such as a single material monoclinic or triclinic? Thanks for your kind advice.

[anisotrpia]

Than you!! It is really clear, but I have read in the literature that to define an order parameter for a liquid crystal is necessary a second order tensor since it is required to have the symmetries of the system (changing n for -n stays the same) so, why can we use a scalar then?

[ankitbioinfo]

Very nice explanation but I did not understand positional OP. What is Z and how to decide the value of a?