Why are there only three components in the stress tensor?
I try to simulation nickel under stress by changing the input cell geometry. However, in the data section of the final result, under “—- Final stress —-”, there are only thee numbers for the stress tensor (in the unit of kbar). There should be 3 x3 = 9 numbers in the stress tensor, as shown when I simulated aluminum. However, there are only three numbers in the stress tensor for nickel. How is that even possible? What could possibly be wrong?