# [Pw_forum] vc-relax

sun jian jasonsun98 at hotmail.com
Tue Sep 12 03:23:21 CEST 2006

```Hi Eric,

It seems that your vc-relax calculation is not finished, it just terminate.
because it not get convergence for the tress tensor or pressure when it get
the max step (n=50).

the way solve this problem is get a more good start geometry or largen the
step maximum.
please specify nstep = 100 or larger in the input file.

good luck!

Best regards,
===============================================
Jian SUN
Physics Dept. of Nanjing University
National Lab. of Solid State Microstructures
Nanjing, Jiangsu Province
210093
China
===============================================

Message: 1
From: "Eric Abel" <etabel at hotmail.com>
To: pw_forum at pwscf.org
Subject: Re:[Pw_forum] vc-relax
Date: Mon, 11 Sep 2006 02:41:02 -0400

Cesar,

Thank you for your response.  Unfortunately if it were that simple, I
wouldn't have had the need to post to the forum.

my output file contains a series of scf calculations, which is to be
expected, after each scf convergence it lists the atomic forces followed by

the stress:

total energy              =  -357.37450532 ryd
estimated scf accuracy    <        2.2E-11 ryd

convergence has been achieved

Forces acting on atoms (Ry/au):

atom   1 type  1   force =     0.00000000    0.00000000    0.00682942
atom   2 type  1   force =     0.00000000    0.00000000   -0.00682942
atom   3 type  2   force =     0.00000000    0.00000000    0.20546159
atom   4 type  2   force =     0.00000000    0.00000000   -0.20546159
atom   5 type  3   force =     0.00000000    0.00000000   -0.08327844
atom   6 type  3   force =     0.00000000    0.00000000    0.08327844

entering subroutine stress ...

total   stress  (ryd/bohr**3)                  (kbar)     P=
-82.53
-0.00135974   0.00000000   0.00000000       -200.02      0.00      0.00
0.00000000  -0.00071001   0.00000000          0.00   -104.45      0.00
0.00000000   0.00000000   0.00038671          0.00      0.00     56.89

after the last iteration, it lists a set of k-points followed by:

Writing file     tiocl.save for program phonon

PWSCF        :    13h57m CPU time

init_run     :    66.55s CPU
electrons    : 44803.10s CPU (      50 calls, 896.062 s avg)
forces       :  1319.61s CPU (      50 calls,  26.392 s avg)
stress       :  2795.36s CPU (      50 calls,  55.907 s avg)

electrons    : 44803.10s CPU (      50 calls, 896.062 s avg)
c_bands      : 37432.39s CPU (     343 calls, 109.132 s avg)
sum_band     :  6668.94s CPU (     343 calls,  19.443 s avg)
v_of_rho     :    70.93s CPU (     688 calls,   0.103 s avg)
newd         :   669.21s CPU (     345 calls,   1.940 s avg)
mix_rho      :    48.63s CPU (     343 calls,   0.142 s avg)

c_bands      : 37432.39s CPU (     343 calls, 109.132 s avg)
init_us_2    :   514.48s CPU (   59025 calls,   0.009 s avg)
cegterg      : 36838.34s CPU (   25725 calls,   1.432 s avg)

sum_band     :  6668.94s CPU (     343 calls,  19.443 s avg)
becsum       :     5.02s CPU (   25725 calls,   0.000 s avg)
addusdens    :   625.36s CPU (     343 calls,   1.823 s avg)

wfcrot       :    44.03s CPU (      75 calls,   0.587 s avg)
cegterg      : 36838.34s CPU (   25725 calls,   1.432 s avg)
h_psi        : 24259.17s CPU (   85747 calls,   0.283 s avg)
g_psi        :   203.06s CPU (   59947 calls,   0.003 s avg)
overlap      :  3791.19s CPU (   59947 calls,   0.063 s avg)
cdiaghg      :  1084.00s CPU (   60022 calls,   0.018 s avg)
update       :  1402.85s CPU (   59947 calls,   0.023 s avg)
last         :  1466.98s CPU (   26082 calls,   0.056 s avg)

h_psi        : 24259.17s CPU (   85747 calls,   0.283 s avg)
init         :    96.39s CPU (   85747 calls,   0.001 s avg)
firstfft     :  8568.69s CPU ( 1932983 calls,   0.004 s avg)
secondfft    :  8659.88s CPU ( 1932983 calls,   0.004 s avg)
add_vuspsi   :  2826.23s CPU (   85747 calls,   0.033 s avg)
s_psi        :  2548.22s CPU (   85747 calls,   0.030 s avg)

General routines
ccalbec      :  4178.90s CPU (  118972 calls,   0.035 s avg)
cft3         :   128.72s CPU (    4378 calls,   0.029 s avg)
cft3s        : 18657.11s CPU ( 4638404 calls,   0.004 s avg)
interpolate  :    33.71s CPU (     688 calls,   0.049 s avg)
davcio       :   147.96s CPU (   84750 calls,   0.002 s avg)

There are a few additional lines, but I don't find the words
CELL_PARAMETERS
or ATOMIC_POSITIONS anywhere.  My instinct tells me that perhaps something
went wrong, but the program completed without complaint.  I never set the
verbosity level, so I assume it's set at the default.  Like I said in my
original post, in the 'relax' calculation, the relevant information was
present.

Any ideas from anyone?

Eric

```