The Tesla for lease or for sale you see at your local car dealership, find great deals on Tesla Leases and Lease Specials on the following Tesla models like Lease a 2015 Tesla Model S $838.00 mo, 2016 Tesla Model X $1,216.12 mo. Search now for Tesla LEASES for sale.
This cannot rigorously be described as sigma-pi conjugation since sigma and pi here refer to different defining planes, and interaction between orbitals of different symmetries (with respect to the same defining plane) is forbidden.
Pi is a number expressing the ratio of the circumference of a perfect circle to its diameter. As there are no perfect circles or spheres in nature (since matter is composed of atoms and is therefore not smooth) the continued extension of pi has long been seen as a harmless exercise of computer power.