CCL:G: Crysallographic structure Vs optimized

 Sent to CCL by: "Hemant Srivastava" [hemantkrsri+*+gmail.com]
 Dear Shabbir,
 For fixing diahedral angle you can write following in input file al last.
 D 1 2 3 4 F
 where 1 2 3 4 are atom numbers.
 For the other problem you have I think you should try different
 method/basis or solvent calculation.
 Hope it will help.
 Hemant Kumar Srivastava,
 The Hebrew University of Jerusalem
 ===================================
 On 8/6/08, Mr shabbir shabbir*_*nenu.edu.cn <owner-chemistry^^ccl.net>
 wrote:
 >
 >  Sent to CCL by: "Mr  shabbir" [shabbir__nenu.edu.cn]
 >  Hello CCL users!
 >  I am a in some confusion want to explain it. Please If some one have an
 idea let me know also.
 >  I have taken a crystallographic structure and optimized it using
 Gaussian03 with C2 symmetry and b3lyp/6-31G* method. After optimization it gave
 me a round about planer structure. After this I have calculated its UV and IR
 spectra that is in good agreement with experimental values but the
 crystallographic structure has a dihedral angle 40 degree with side pyrrol rings
 which is not in my optimized structure. So can I say that my Gassphase optimized
 structure is reliable on the basis of calculated experimental values and start
 my futher calculations? Secondly I tried to freeze that dihedral angle using
 guessview but it could not freeze during optimization. How to freeze dihedral
 angle during optimization so that it will not change during calculations?
 >   Mr.Shabbir
 >  Northeast normal university Changchun
 >  P.R.China
 >  shabbir++nenu.edu.cn>
 >
 >