If you read carefully, it's noted that 0.77W/GH would be ceiling due to node jump, not taking any optimization or correction into consideration. The actual numbers are lower, and the ~0.6W/GH was number we decided that was closest to reality + error margin.
Regards,
Nasser
What is the load capacitance and beta values for the transistors in the process your using? What's the V
tn?