[CPMD-list] problem reading restart of a QM/MM calculation

[Xevi Biarnés (PCB)]

dear all,

I am experiencing a problem when trying to start a MD QM/MM simulation,
restarting from a previously converged wavefunction. 
(please, note this is an unrestricted calculation (LSD)).


1) I optimize wavefunction after few steps of PCG MINIMIZE combined with
ODIIS, and these are the final results:

****************************************************************


 ELECTRONIC GRADIENT:
    MAX. COMPONENT =    5.16534E-06         NORM =    2.76716E-07

 TOTAL INTEGRATED ELECTRONIC DENSITY
    IN G-SPACE =                                       418.000000
    IN R-SPACE =                                       418.000000
 TOTAL INTEGRATED SPIN DENSITY                            .000000
 TOTAL INTEGRATED ABSOLUTE VALUE OF SPIN DENSITY          .104658

 (K+E1+L+N+X)           TOTAL ENERGY =         -971.56445047 A.U.
 (K)                  KINETIC ENERGY =            6.56975448 A.U.
 (E1=A-S+R)     ELECTROSTATIC ENERGY =         -510.04072896 A.U.
 (S)                           ESELF =          547.54827985 A.U.
 (R)                             ESR =           29.55261354 A.U.
 (L)    LOCAL PSEUDOPOTENTIAL ENERGY =         -465.61658066 A.U.
 (N)      N-L PSEUDOPOTENTIAL ENERGY =           13.84694329 A.U.
 (X)     EXCHANGE-CORRELATION ENERGY =         -194.59619865 A.U.
         GRADIENT CORRECTION ENERGY =            -4.47332126 A.U.

 ****************************************************************


no problem up to here... but...

2) when I try to restart from this calculation and run MD, it seems that the
program doesn't read properly the RESTART file, because at the very initial
first step, the energy is MUCH different (specially the kinetic energy of KS
orbitals), and the electronic structure seems completely different:


TOTAL INTEGRATED ELECTRONIC DENSITY
    IN G-SPACE =                                       418.000000
    IN R-SPACE =                                       418.000000
 TOTAL INTEGRATED SPIN DENSITY                            .000000
 TOTAL INTEGRATED ABSOLUTE VALUE OF SPIN DENSITY          .355959

 (K+E1+L+N+X)           TOTAL ENERGY =         -964.82567117 A.U.
 (K)                  KINETIC ENERGY =          516.31585370 A.U.
 (E1=A-S+R)     ELECTROSTATIC ENERGY =         -510.06307260 A.U.
 (S)                           ESELF =          547.54827985 A.U.
 (R)                             ESR =           29.58196044 A.U.
 (L)    LOCAL PSEUDOPOTENTIAL ENERGY =         -465.39399883 A.U.
 (N)      N-L PSEUDOPOTENTIAL ENERGY =           14.31292073 A.U.
 (X)     EXCHANGE-CORRELATION ENERGY =         -194.45583778 A.U.
         GRADIENT CORRECTION ENERGY =            -4.51407495 A.U.

       NFI    EKINC   TEMPP           EKS      ECLASSIC          EHAM
EQM         DIS    TCPU
         1  4.64892   599.9    -964.82567    -826.26423    -821.61531
-639.28413    .457E-04   61.69
         2  1.39480   599.5    -960.96048    -822.48436    -821.08956
-635.51214    .183E-03   51.09
         3  6.32274   598.9    -967.08644    -828.74469    -822.42195
-641.71962    .409E-03   51.32
         4  6.22402   598.2    -966.45663    -828.29024    -822.06622
-641.22766    .722E-03   49.62
         5  3.57136   597.3    -962.88023    -824.92367    -821.35232
-637.84486    .112E-02   51.37
         6  5.64465   596.2    -965.46495    -827.74828    -822.10363
-640.63798    .160E-02   53.29



I can ensure that the coordinates are the same in both runs, and that I am
using the same RESTART file. Why is electronic structure so far from ground
state at the very beginning?? (look at the very high value of EKINC!!!)

Maybe it's not a problem of reading the restart. I was wondering whether
when MD is set up, new interactions with the electronic density come into
account, that were not previously considered with a simple OPTIMIZE
WAVEFUNCTION calculation. In this case, maybe there's a strong interaction,
that is only considered when running MD (and not OPT WF), and this "pulls"
the electronic system at the very beginning step of MD. I don't know...
these are speculations...

Did anybody experience similar problems?? Do you have any suggestions??

(I attached both full input and output files)

Thanks a lot for your help!

see you!


Xevi  =o)
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