What is GMEC (Global Minimum Energy Conformation)?
Yes. It is the conformer with the lowest energy out of all possible conformers.

There are also local minima which have a lower energy than conformations either side of the them on the energy diagram but do not have the lowest possible energy.



In this diagram showing the conformers of butane we can see that all three stable conformers; the two gauche conformers and the anti conformer are at local energy minima but the anti conformer is the global minimum.