[Pw_forum] turbo_lanczos.x returns error

Timrov Iurii iurii.timrov at epfl.ch
Thu Jul 28 09:27:48 CEST 2016

Dear Sunghwan Choi,

It seems that the turbo_lanczos.x code crashes, because you included some empty states in the calculations. From your output we can see "Warning: There are virtual states in the input file, trying to disregard in response calculation"?. In TDDFPT of Quantum ESPRESSO 5.4.0 there is a bug, when one tries to include some empty states. This bug was discussed on the pw_forum a few days ago: http://qe-forge.org/pipermail/pw_forum/2016-July/110476.html

and this bug was already fixed in the SVN version on qe-forge.

In order to solve your problem in 5.4.0, just do not specify the parameter "nbnd" in the input file for PWscf calculation, and the code by default will compute only the occupied states (i.e. all what is needed for turbo_lanczos.x).

Please let us know is this works.

Best regards,


Dr. Iurii Timrov
Postdoctoral Researcher
Swiss Federal Institute of Technology Lausanne (EPFL)
Laboratory of Theory and Simulation of Materials (THEOS)
CH-1015 Lausanne, Switzerland
+41 21 69 34 881
From: pw_forum-bounces at pwscf.org <pw_forum-bounces at pwscf.org> on behalf of SungHwan Choi <sunghwanchoi91 at gmail.com>
Sent: Thursday, July 28, 2016 8:22 AM
To: PWSCF Forum
Subject: [Pw_forum] turbo_lanczos.x returns error

Dear all,
I had originally work fine with turboTDDFT package. I recently change the machine and install 5.4.0 version. pw.x looks okay but for lanczos calculation  I faced the error. It seems easy problem but I cannot solve it. error message from turbo_lanczos is

     Subspace diagonalization in iterative solution of the eigenvalue problem:
     a serial algorithm will be used

     Warning: There are virtual states in the input file, trying to disregard in response calculation

     Normal read

     Gamma point algorithm


     Number of Lanczos iterations =   1500

     Starting Lanczos loop        1

     Lanczos iteration:      1   Pol:1
     lr_apply_liouvillian: not applying interaction
     alpha(00000001)=  0.000000
     beta (00000001)=  3.859102
     gamma(00000001)=  3.859102
     z1=       1  0.000000000000000E+00  0.000000000000000E+00
     z1=       2  0.000000000000000E+00  0.000000000000000E+00
     z1=       3  0.000000000000000E+00  0.000000000000000E+00

     Error in routine davcio (22):
     error while writing from file "/home/udg2/kse/test_shchoi/./out/Benzene.restart_lanczos.11"

     stopping ...

     Error in routine davcio (22):
     error while writing from file "/home/udg2/kse/test_shchoi/./out/Benzene.restart_lanczos.12"

I think writing error on out directory but I pw.x calculation was finished well.
here is input file for this result

  prefix = 'Benzene',
  outdir = './out',
  restart_step = 250,
  restart = .false.,
  itermax = 1500,
  ipol = 4

It should work. but I don't know why it does not work. I check there is enough space on the disk. If you have some pieces of advice, please let me know
Sunghwan Choi

Sunghwan Choi
Ph.D candidate
Computational Quantum Molecular Science Lab
Department of Chemistry, KAIST, Republic of Korea

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