[QE-users] ph.x calculation with DPT+U

[Timrov Iurii]

Dear Liang,


> It is very slow, it is normal?


Yes


> My system consists of 80 atoms...


For such a large system DFPT+U is expected to be very slow, in particular because the calculation of d2ns_bare matrix (second "bare" derivative of the occupation matrix ns) is computationally very expensive. I suggest to use the frozen-phonon approach (Phonopy).


Greetings,

Iurii


--
Dr. Iurii TIMROV
Postdoctoral Researcher
STI - IMX - THEOS and NCCR - MARVEL
Swiss Federal Institute of Technology Lausanne (EPFL)
CH-1015 Lausanne, Switzerland
+41 21 69 34 881
http://people.epfl.ch/265334
________________________________
From: users <users-bounces at lists.quantum-espresso.org> on behalf of LEUNG Clarence <liangxy123 at hotmail.com>
Sent: Saturday, October 17, 2020 8:53:18 AM
To: users at lists.quantum-espresso.org
Subject: [QE-users] ph.x calculation with DPT+U

Dear QEusers,

Recently, I do ph.x calculation with DPT+U in QE6.6. However, it is very very slow. The output file running for four days as follows:

     Atomic wfc used for the projector on the Hubbard manifold are NOT orthogonalized

     Calculating the dnsbare matrix...

     Calculating the dnsorth_cart matrix...

     Alpha used in Ewald sum =   2.8000

     Calculating the d2ns_bare matrix. It might take a while!
     k point #     1   out of     2

The specification of my server is two nodes with 64 cores (Xeon e5) and 512G RAMs. My system consists of 80 atoms, and the input files of ph.x si as follows:

&INPUTPH
  outdir='',
  prefix='',
  tr2_ph = 1d-12,
  ldisp = .true. ,
  fildyn ='' ,
  epsil=.false.,
  trans=.true.,
  nq1 = 1 ,
  nq2 = 1 ,
  nq3 = 1 ,
  nat_todo = 1,
  alpha_mix(1) = 0.07,
/
79

It is very slow, it is normal? It is very appreciated that give me some advices.

Best regards,
LIANG
Postdoc
City University of Hong Kong
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