[CPMD-list] md-run: crystal seems to explode

[Axel Kohlmeyer]

On Thu, 3 Mar 2005 Nico.Zobel at TU-Berlin.DE wrote:


NZ> AK> NZ>  NUMBER OF STATES:                                            164
NZ> AK> NZ>  NUMBER OF ELECTRONS:                                   327.00000
NZ> AK> NZ>  CHARGE:                                                   .00000
NZ> AK>
NZ> AK> oooops. you have an odd number of electrons. i.e. you'll either need to
NZ> AK> adjust the charge of your system or run an 'open-shell' calculation by
NZ> AK> using the LSD keyword in the &CPMD section. note, that with LSD and PBE
NZ> AK> you'll need an update to your CPMD code. i'll attach a patch with
NZ> AK> the changes that will be in cpmd-v3.9.2, but it may not apply cleanly
NZ> AK> to the pristine cpmd-v3.9.1 sources (there were some overlapping
NZ> AK> other changes), YMMV.
NZ> 
NZ> As mentioned above, I could not test the patch so far. That is why I added
NZ> one electron by setting CHARGE to -1.
NZ> Do you think adding that electron leads to a significant change in the
NZ> chemical behaviour of my system? (I want to estimate activation energy by
NZ> blue-moon-ensemble method)
NZ> In other words:
NZ> If the patch does not apply cleanly (as you mentioned), can I still get
NZ> reasonable results by adding that electron?

adding or removing an electron does change the chemistry of your
system significantly. shuffling electrons around, is what 
chemistry is mostly about. there is a huge difference in the
chemistry of, say, a mg+ and an mg++ ion. you need to know
the the total charge of your system first. if that results 
in an odd number of electrons, you _have_ to use LSD (or use
a different compound).

[...]

NZ> AK> NZ>    ============================================================
NZ> AK> NZ>    |  pseudopotential report: version  7.3.5 date 10-15-2004  |
NZ> AK> NZ>    ------------------------------------------------------------
NZ> AK> NZ>    |  mg (Vol05)           PBE - GGA           exchange-corr  |
NZ> AK> NZ>    |  z =  12.00  zv =   2.00  exfact =   5.00000             |
NZ> AK> NZ>    |                            etot  =  -1.65416             |
NZ> AK> NZ>    |  index    orbital      occupation    energy              |
NZ> AK> NZ>    |    1        300           2.00        -.35               |
NZ> AK> NZ>    |  keyps = 3     ifpcor = 0                                |
NZ> AK> NZ>    |  rinner =      1.43     for L=    1                      |
NZ> AK> NZ>    |  rinner =      1.43     for L=    2                      |
NZ> AK> NZ>    |  rinner =      1.43     for L=    3                      |
NZ> AK> NZ>    |    new generation scheme:                                |
NZ> AK> NZ>    |    nbeta =  4     kkbeta =  583     rcloc =    3.1000    |
NZ> AK> NZ>    |    ibeta     l     epsilon   rcut iptype                 |
NZ> AK> NZ>    |       1      0        .00   3.00      0                  |
NZ> AK> NZ>    |       2      0       -.35   3.00      0                  |
NZ> AK> NZ>    |       3      1        .00   3.00      2                  |
NZ> AK> NZ>    |       4      1       -.35   3.00      2                  |
NZ> AK> NZ>    |  npf    = 6  ptryc =   8.000                             |
NZ> AK> NZ>    |  lloc   = 2  eloc   =    .000                            |
NZ> AK> NZ>    |  ifqopt = 3  nqf    = 6  qtryc =   8.000                 |
NZ> AK> NZ>    |  all electron calculation used koelling-harmon equation  |
NZ> AK> NZ>    |         ************logarithmic mesh************         |
NZ> AK> NZ>    ============================================================
NZ> AK>
NZ> AK> i am not 100% certain, that your mg-pseudo is compatible with cpmd.
NZ> AK> could you pleas apply the second attached patch to make the uspp
NZ> AK> reader reject incompatible potential files. this patch should also
NZ> AK> work for people still using v3.7.2, btw.

NZ> Again: This patch has not been tested, either.

in contrast to the other, it should apply cleanly.

NZ> My question is:
NZ> Which parameter(s) of the pseudopotential make you think that it might be
NZ> incompatible?

the fact that the s-projectors do not have the same iptype as
the p-projectors. all uspps that i know to be working have
them all set to the same value (iptype 2).
this is just a wild guess, though.

regards,
	axel.

NZ> Maybe I can easily adjust the PP (i.e. the parameters in Vanderbilt's
NZ> code) to make it compatible ...
NZ> 
NZ> Thank you very much in advance -
NZ> Nico.
NZ> 
NZ> 

-- 

=======================================================================
Dr. Axel Kohlmeyer   e-mail: axel.kohlmeyer at theochem.ruhr-uni-bochum.de
Lehrstuhl fuer Theoretische Chemie          Phone: ++49 (0)234/32-26673
Ruhr-Universitaet Bochum - NC 03/53         Fax:   ++49 (0)234/32-14045
D-44780 Bochum  http://www.theochem.ruhr-uni-bochum.de/~axel.kohlmeyer/
=======================================================================
If you make something idiot-proof, the universe creates a better idiot.