[CPMD-list] Convergence is still too bad !!
Juerg Hutter
hutter at pci.unizh.ch
Fri Apr 4 14:43:53 CEST 2003
Hi
if in a PCG MINIMIZE optimisation Lambda for the
line search is smaller than 10**-2 there is a
severe problem and the job should be stopped.
I can't see exactly what the problem in your case
is, but to set GC-CUTOFF to 10**-6 in a USPP
calculation of an isolated molecule is certainly
a good idea. I also see that you have set
STATES to 5, one more than required.
This introduces an additional state not needed
in the optimisation. It's possible that this
confuses the optimiser. On the other hand you
say that it worked without problems using other PP.
Still I would only use occupied states in a
standard optimisation.
Juerg
----------------------------------------------------------
Juerg Hutter Phone : ++41 1 635 4491
Physical Chemistry Institute FAX : ++41 1 635 6838
University of Zurich E-mail: hutter at pci.unizh.ch
Winterthurerstrasse 190
CH-8057 Zurich, Switzerland
----------------------------------------------------------
On Thu, 3 Apr 2003, Du Aijun wrote:
> Dear all,
>
> When I performed a geomertry optimization on methane(CH4) molecule using
> Vanderbilt ultrasoft pseudopotential and PCG MINIMIZE, I found the maximum
> gradient of wavefunction grows bigger at first serveral steps, but keep
> constant later. The problems are as following:
>
> LINE SEARCH : LAMBDA=.281 ENERGY = -7.9000653
> 1 2.752E-02 4.714E-03 -7.897058 -7.897E+00 25.17
> LINE SEARCH : LAMBDA=.422 ENERGY = -7.9589492
> 2 2.887E-02 4.662E-03 -7.900065 -3.008E-03 25.24
> LINE SEARCH : LAMBDA=.107 ENERGY = -7.9773182
> 3 6.313E-02 3.395E-03 -7.958926 -5.886E-02 25.22
> LINE SEARCH : LAMBDA=.176E-02 ENERGY = -7.9760463
> 4 9.486E-02 2.432E-03 -7.977438 -1.851E-02 25.18
> LINE SEARCH : LAMBDA=.330E-03 ENERGY = -7.9757286
> 5 9.847E-02 2.356E-03 -7.976233 1.205E-03 25.21
> LINE SEARCH : LAMBDA=.618E-04 ENERGY = -7.9755948
> 6 9.922E-02 2.343E-03 -7.975730 5.031E-04 25.21
> LINE SEARCH : LAMBDA=.116E-04 ENERGY = -7.9755623
> 7 9.937E-02 2.340E-03 -7.975595 1.354E-04 25.14
> LINE SEARCH : LAMBDA=.217E-05 ENERGY = -7.9755550
> 8 9.940E-02 2.339E-03 -7.975562 3.244E-05 25.11
> LINE SEARCH : LAMBDA=.407E-06 ENERGY = -7.9755533
> 9 9.941E-02 2.339E-03 -7.975555 7.374E-06 25.26
> LINE SEARCH : LAMBDA=.764E-07 ENERGY = -7.9755530
> 10 9.941E-02 2.339E-03 -7.975553 1.623E-06 25.10
> .................................................................
> .................................................................
> 997 9.941E-02 2.339E-03 -7.975552 -8.882E-16 25.23
> LINE SEARCH : LAMBDA=.525-157 ENERGY = -7.9755518
> 998 9.941E-02 2.339E-03 -7.975552 8.882E-16 25.21
> LINE SEARCH : LAMBDA=.262-157 ENERGY = -7.9755518
> 999 9.941E-02 2.339E-03 -7.975552 -8.882E-16 25.15
> LINE SEARCH : LAMBDA=.590-157 ENERGY = -7.9755518
> 1000 9.941E-02 2.339E-03 -7.975552 8.882E-16 25.17
> ================================================================
> = END OF GEOMETRY OPTIMIZATION =
> ================================================================
>
> The following is my first time input file:
>
> &CPMD
> OPTIMIZE GEOMETRY
> HESSIAN UNIT
> BFGS
> PCG MINIMIZE
> CONVERGENCE
> 1.0D-4 5.0D-4
> CENTER MOLECULE
> MAXSTEP
> 1000
> &END
>
>
> &DFT
> NEWCODE
> FUNCTIONAL PBE
> GC_CUTOFF
> 0.2E-07
> &END
>
> &SYSTEM
> ANGSTROM
> pOSSION SOLVER TUCKERMAN
> SYMMETRY
> 0
> CELL
> 13.0 1.0 1.0 0 0 0
> CUTOFF
> 30.0
> STATES
> 5
> CHARGE
> 0.0
> TESR
> 2
> &END
> &ATOMS
> *006-C-gpbe--bm.uspp NEWF BINARY
> LMAX=P
> 1
> -4.3985 1.5414 0.0000
> *001-H-gpbe--bm.uspp BINARY NEWF
> LMAX=S
> 4
> -3.3985 1.5414 0.0000
> -4.7323 2.4840 0.0000
> -4.7323 1.0701 0.8164
> -4.7323 1.0701 -0.8164
> &END
>
> Then I made some changes on my input file according to the suggestion from
> others:
>
> Adding INITIALIZE WAVEFUNCTION RANDOM in the section of $CPMD..... $END!
> Increasing GC-CUTOFF to 5.D-5. But problem still exists and the only
> difference is that the gradient become a new constant!
>
> I also changed the Convergence standard to 1.D-3 and 1.D-3 to pass several
> Geometry steps first.Then I restart the calculation with 1.D-5 and 5.D-5.
> But the same Problems still met! In addition, bad convergence were also
> observed when using another Vanderbilt potential(pw91 not PBE). All the
> uspps inputfile are from inputfile
> http://www.physics.rutgers.edu/~dhv/uspp/uspp-cur/Work/
>
> When I use other pseudopotential in the PP_LIBRARY provide by www.cpmd.org,
> such as BLYP. It is very fast to reach convergence.
>
> Could anyone help me solve this problem? Any comments and suggestions would
> be highly appreciated!
>
> With regards,
> A.J.Du
>
>
>
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