[CPMD-list] Problems optimizing monoclinic unit cell

[Ewald Pauwels]

Dear all,

Does anybody have any experience with applying CPMD on monoclinic crystals?
The system I am studying contains four (organic) molecules in the unit 
cell. When I optimize these molecules (only the atomic coordinates - not 
the cell constants), I find that the unit cell no longer satisfies the 
original symmetry. I.e. all four molecules have a substantially 
different conformation!

I suspect that I must be doing something wrong here. Below is my inputfile.


Thanks in advance,
Ewald.



-------------------------------------------------------
inputfile
-------------------------------------------------------
&CPMD
 RESTART LATEST GEOFILE WAVEFUNCTION
 OPTIMIZE GEOMETRY
 LSD
 ODIIS NO_RESET=50
  10
 TIMESTEP
  20
 PRINT
  10
 STRUCTURE BONDS ANGLES
&END

&SYSTEM
 ANGSTROM
 SYMMETRY
 12
 CELL
 5.0872  2.314338  1.073321  0.0  -0.374493314  0.0
 CUTOFF
 25.
 MULTIPLICITY
 1
&END

&ATOMS
*C_VDB_U BINARY NEWF
 LMAX=P
 8
  0.218182218417937  1.473520453  0.333090471110274
  0.732546560623109  1.717103823  -1.08374897292691
  1.30308357695184  7.360020453  2.1982999039374
  0.788719234746671  7.603603823  3.61513934797459
  -0.218182218417937  -1.473520453  -0.333090471110274
  -0.732546560623109  -1.717103823  1.08374897292691
  1.73944801378772  4.412979547  2.86448084615795
  2.25381235599289  4.169396177  1.44764140212077
*N_VDB_U BINARY NEWF
 LMAX=P
 4
  2.03113800324446  1.040509513  -1.31410549705625
  -0.509872207874679  6.927009513  3.84549587210393
  -2.03113800324446  -1.040509513  1.31410549705625
  3.55240379861424  4.845990487  1.21728487799143
*O_VDB_U BINARY NEWF
 LMAX=P
 8
  1.05333382374583  1.104201443  1.19695275049904
  -1.00750738194352  1.676251513  0.53944941448416
  0.467931971623952  6.990701443  1.33443762454863
  2.5287731773133  7.562751513  1.99194096056352
  -1.05333382374583  -1.104201443  -1.19695275049904
  1.00750738194352  -1.676251513  -0.53944941448416
  2.57459961911561  4.782298557  3.72834312554672
  0.513758413426261  4.210248487  3.07083978953184
*H_VDB_U BINARY NEWF
 LMAX=S
 20
  2.33817143317496  1.18130282  -2.29299415508719
  2.75812420631155  1.37791192  -0.67745575495101
  1.93653355901116  0.03473035  -1.14763114043162
  0.875530385150063  2.77889892  -1.22357285168305
  0.0131007466085907  1.35318862  -1.81758891709173
  -0.816905637805185  7.06780282  4.82438453013487
  -1.23685841094177  7.26441192  3.20884612999869
  -0.415267763641377  5.92123035  3.67902151547929
  0.645735410219716  8.66539892  3.75496322673072
  1.50816504876119  7.23968862  4.34897929213941
  -2.33817143317496  -1.18130282  2.29299415508719
  -2.75812420631155  -1.37791192  0.67745575495101
  -1.93653355901116  -0.03473035  1.14763114043162
  -0.875530385150063  -2.77889892  1.22357285168305
  -0.0131007466085907  -1.35318862  1.81758891709173
  3.85943722854474  4.70519718  0.23839621996049
  4.27939000168133  4.50858808  1.85393462009667
  3.45779935438094  5.85176965  1.38375923461606
  2.39679618051984  3.10760108  1.30781752336463
  1.53436654197837  4.53331138  0.713801457955944
&END

&DFT
 LDA CORRELATION PZ
 FUNCTIONAL BP
 GC-CUTOFF
 5.D-5
&END
------------------------------------------------------------------






-- 
Ewald Pauwels
Centre for Molecular Modelling
Laboratory of Theoretical Physics
Ghent University
Proeftuinstraat 86
B-9000 Gent
Belgium
ewald.pauwels at UGent.be
+32 9 264 65 76