Check my IIP2 simulation method using QPSS + QPAC

Good afternoon everybody!
Last night I simulated IIP2 use QPSS+QPAC, In the Direct Plot Plot I choose 2rd, and selected 2nd order Harmonic 1.3999G -1 -1 and 1st order Harmonic 1.4001G 1 -1.The sim parameters :fRF=1.401G fLO=1.4G, the second tone is 1.4011G. so fIF=1MHz.But the waveform was strange. Is this sim method right? Why is IIP2 so small? How to sim IIP2?

it is wrong one. for the nonlinearity simu of downmixer, harmonics are all in the low frequency part

I know IM2 signal is located near the LO frequence(fLO±(fRF1-fRF2)) and so it is easily filtered by LPF. In a ZIF receiver, the IM2 influences the output by adding to the output without mixing with RF signal. so I am confused by the importance of IIP2, I think isolation is very critical.

If it's wrong, how to simu IIP2?

you are wrong
it should be fRF1-fRF2, and it will not be filtered out by LPF. it will affect ZIF performance greatly.

yes, you are right the fRF1-fRF2 will present at the IF port without frequency translate.