[CPMD-list] Problems on convergence!!

[duaj at fudan.edu]

Dear all,

When I perform a geomertry optimization on methane(CH4) molecule using 
Vanderbilt ultrasoft pseudopotential and PCG MINIMIZE. When optimizing 
wavefunction, 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 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

Can someone help me to solve this problem? Many thanks in advance!

Regards,
Adain

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