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Posted: **Thu May 15, 2025 9:52 pm**

VASP team,

In the wiki on the GW approximation, we see the example output for a G0W0R calculation.

QP shifts evaluated in KS or natural orbital/ Bruckner basis
  k-point   1 :       0.0000    0.0000    0.0000
  band No.  KS-energies   sigma(KS)    QP-e(linear)    Z         QP-e(zeros)     Z        occupation    Imag(E_QP)    QP_DIFF TAG
 
       1      -7.1627      -8.6732      -8.2451       0.7166      -8.2346       0.7026       2.0000      -1.3101       0.0000   2
       2      -2.0901      -3.4155      -3.0350       0.7129      -3.0272       0.7011       2.0000      -0.5582      -0.0000   2
       3      -2.0901      -3.4155      -3.0350       0.7129      -3.0272       0.7011       2.0000      -0.5582       0.0000   2
       4      -2.0901      -3.4155      -3.0350       0.7129      -3.0272       0.7011       2.0000      -0.5582      -0.0000   2
       5       0.4603      -0.8219      -0.4904       0.7414      -0.4814       0.7273       2.0000      -0.1902       0.0000   2
       6       0.4603      -0.8219      -0.4904       0.7414      -0.4814       0.7273       2.0000      -0.1902      -0.0000   2

The Imag(E_QP) column is labeled as "imaginary part of complex pole \(\omega\), i.e. measure for inverse lifetime of quasi-particle".

My question is how is Imag(E_QP) related to the inverse lifetime? Is it just a factor of \(\frac{2}{\hbar}\)? And how is Imag(E_QP) related to \(\mathrm{Im}\Sigma\)? Thanks!

Brian

Posted: **Fri May 16, 2025 11:56 am**

Dear bprobinson102,

Imag( E_QP) is the imaginary part of the poles of the Green's function. In EVGW0 the imaginary part of these poles is equivalent to the imaginary part of the self-energy. The inverse of the imaginary part of the self-energy is proportional to the life time of the quasi particle. The lifetime of your quasi particle is then given by tau = hbar/(2 Im(Sigma)).

All the best Jonathan

Posted: **Fri May 16, 2025 3:28 pm**

Jonathan,

Thank you!

Brian

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G0W0R output clarification

G0W0R output clarification

Re: G0W0R output clarification

Re: G0W0R output clarification