[Pw_forum] questions about negative charge and extrapolation

[Eduardo Ariel Menendez P]

Hi,
I am curious about these  warning messages

    Writing output data file cdteo3_80-3000p.save
     Check: negative starting charge=   -0.400082
Is it due to the FFT? The total charge is 576

     second order charge density extrapolation
     Check: negative starting charge=   -0.410292
Same question

     negative rho (up, down):  0.425E+00 0.000E+00
     second order wave-functions extrapolation

     Message from extrapolate_wfcs:
     the matrix <psi(t-dt)|psi(t)> has 69 zero eigenvalues

does it means that is better no to extrapolate?

Thanks
Eduardo