[CPMD-list] Problems optimizing monoclinic unit cell

[Ewald Pauwels]

Dear Bala,

Thank you very much for pointing out my problem. I have redone some test 
calculations and the conformations of the four molecules in my unit cell 
are now virtually identical!

Perhaps one further question on this matter is why to put the 'cos beta' 
value first (i.e. on position d)? Is there a specific reason for this 
choice?

Thanks,
Ewald.


Dr. Balasubramanian Sundaram wrote:

>Dear Ewald,
>    We have been doing geometry optimization (ion coordinates) in 
>a monoclinic cell, without problems. Our CPMD version 3.9.1. 
>I feel that the following lines in your input file may not be correct.
>
>  
>
>>CELL
>>5.0872  2.314338  1.073321  0.0  -0.374493314  0.0
>>    
>>
>
>In the new version (v. 3.9.1), in file "sysin.F", there are a few lines
>that
>say:
>      ELSE IF (IBRAV.EQ.12) THEN
>         IF ((ABS(CELLDM(5)).GT.BOXEPS)
>     $        .OR.(ABS(CELLDM(6)).GT.BOXEPS)) THEN
>            WRITE(0,*) 'SUPERCELL IS NOT MONOCLINIC'
>            WRITE(0,'(A,A)') 'EXPECTED FORM:',
>     $           ' a b c d 0.0 0.0'
>            CELLOK=.FALSE.
>         ENDIF
>
>It appears that the correct way to put the cell info for you would be:
>
>  
>
>>CELL
>>5.0872  2.314338  1.073321 -0.374493314  0.0 0.0
>>    
>>
>
>The previous version (v. 3.7.2) did not have this check and error msg. 
>This is probably a reason why the molecular conformation got messy.
>
>Best Wishes,
>Bala
>
>
>
>Ewald Pauwels wrote:
>  
>
>>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
>>
>>_______________________________________________
>>CPMD-list mailing list
>>CPMD-list at cpmd.org
>>http://cpmd.org/mailman/listinfo/cpmd-list
>>    
>>


-- 
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

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