For a phospholipid, the critical packing parameter is given by: $$P=\frac{v}{a_0l_c}$$ And I know that
- $v$ is the volume of the hydrocarbon tail.
- $l_c$ is the critical length of the hydrocarbon chains.
- $a_0$ is the optimum surface area of the head group.
But what do these actually mean?
For example what is the volume of the hydrocarbon tail, since it can't be simply the volume of all the atoms that make it up else this would be negligible? What is the critical length of the hydrocarbon tail? And What is the optimum surface area of the head group?