[molpro-user] Error: SPIN not possible

"Piotr J. Bardziński" bardzinski at poczta.fm
Wed Feb 1 14:37:18 GMT 2012

Dear Grant, Ed and Ornellas,

Thank you for your quick response. The point is that my molecule is like
ammonium, where all electrons are paired, but
the overall molecule has a positive charge. Namely, in the case of
ammonium, one extra proton "takes" one electron from the nitrogen` 2s
orbital, yielding the configuration of nitrogen atom in a molecule to be
[He]2s1 2p3, but the total number of electrons in a molecule remains the
same. In my case, I got two similar interacting molecules,  in which
ammonium hydrogen atoms were substituted with aliphatic chains, so it
seems that one of the carbons bound to nitrogen must lack an electron
and accept one from nitrogen. So, I calculated that each molecule must
have 178 electrons and the system is closed shell. But the charge of
molecule is +1... So today, I ran the input with following preamble:

***,  input

...but I am uncertain, if it is enough to declare the closed shell sytem
with +1 charge per each of two molecules. Am I did it in a proper way?

Best regards,
Piotr B.

W dniu 2012-02-01 13:53, frornell at usp.br pisze:
>  Dear Piotr,
>  You have an odd number of electrons (177), so you can not have a
>  system with spin = 0.
>  Ornellas
>  Citando "Piotr J. Bardzi?ski"<bardzinski at poczta.fm>:
>>  Dear Listmembers,
>>  Sorry to bother you in the matter of my interest, but I am a Molpro
>>  user and have a problem I can`t fix.
>>  I would appreciate it if you would mind advise me how to deal with
>>  that... Namely, I want to perform an RI-MP2
>>  calculation of interaction energy between two quarternary ammonium
>>  ions with one long aliphatic chain.
>>  Here is the error communicate extracted from the end of output file:
>>  nelec= 177  ms2=   0
>>  ? Error
>>  ? SPIN not possible
>>  ? The problem occurs in putocc
>>  GLOBAL ERROR fehler on processor   0
>>  Note hat the input lines were:
>>  ***,
>>  memory,175,m
>>  gdirect
>>  basis=cc-pVDZ
>>  wf,charge=2,symmetry=1,spin=0
>>  geomtyp=xyz
>>  nosym,noorient
>>  geometry={
>>  (...)
>>  df-hf,df_basis=vtz
>>  df-mp2
>>  As I neither have an idea what to do with that, nor found any
>>  solution on the internet forums, I`ve decided to ask you, this question.
>>  I would be grateful if you look at my case...
>>  Best regards!
>>  Piotr B
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