# Mulliken charge problem

obo bo... at matcalc.de
Mon Aug 3 10:23:15 CEST 2009

```Dear cp2k Users,
I've made some calculations with alpha quarz. At first I have
optimized the hexagonal cell with 9 atoms. I've got the initial
coordinates from a cell optimization in another ab initio programm.
The relaxation in cp2k was sucessfull and the mulliken charges from
the Si atoms are approximately the same. Now I have constructed an
orthorhombic cell with 19 atoms. I've constructed the basis from the
coordinates of the relaxed hexagonal cell. The length of the cell
vectors are also calculated from the hexagonal cell vectors(a, 3^0.5,
c).
When I start the cell optimization, I get the following mulliken
charges:
Atom     |    Charge
1  Si    1.370421
2  Si    1.349422
3  Si    0.726644
4  O    -0.611734
5  O    -0.644209
6  O    -0.595641
7  O    -0.609976
8  O    -0.586622
9  O    -0.647799
10  Si    1.473611
11  Si    1.489633
12  Si    0.829598
13  O    -0.609031
14  O    -0.568553
15  O    -0.591643
16  O    -0.610546
17  O    -0.600818
18  O    -0.562758
Total       0.000000

At the end of the cell optimization, the relation between the cell
vectors (a and 3^0.5*a) are also wrong.
What is my mistake??? Can somebody help me?

The input file:

&FORCE_EVAL
METHOD Quickstep
STRESS_TENSOR NUMERICAL
&DFT
&POISSON
PERIODIC XYZ
POISSON_SOLVER PERIODIC
&EWALD
EWALD_TYPE SPME
&END
&END POISSON
&MGRID
CUTOFF 650
RELATIVE_CUTOFF 85.0
&END MGRID
&QS
WF_INTERPOLATION PS
EXTRAPOLATION_ORDER 4
&END QS
&SCF
EPS_SCF 1.E-6
CHOLESKY OFF
MAX_SCF 50
SCF_GUESS ATOMIC
&OUTER_SCF
DIIS_BUFFER_LENGTH 5
OPTIMIZER DIIS
&END OUTER_SCF
&END SCF
&XC
&XC_GRID
XC_DERIV SPLINE3
&END XC_GRID
&XC_FUNCTIONAL PBE
&END XC_FUNCTIONAL
&END XC
&END DFT
&SUBSYS
&CELL
PERIODIC XYZ
MULTIPLE_UNIT_CELL 1 1 1
ABC 4.805 8.3225 5.393
ALPHA_BETA_GAMMA  90.0 90.0 90.0
&END CELL
&COORD
Si 1.1328078594000004 6.4061604696       3.5954303785000006
Si 1.1329589190000002 1.9039591092000003 1.7978168006000006
Si 2.6289910789000004 8.3163249591       5.3929132817
O 1.6426232969999999  7.8451213509999995 4.154876766399999
O 4.4371215705        1.6255884538000005 2.3576057410000004
O 3.6202186447        7.155568958499999  0.5597043610000001
O 1.6427913173999997  0.4650789015000002 1.237976828999999
O 3.620111714099999   1.1547964305000002 4.8334310334
O 4.4368490245        6.684213627799998  3.035570217399999
Si 3.4358078594       2.2346604696       3.5954303785000006
Si 3.435958918999999  6.054959109200001  1.7978168006000006
Si 0.1269910789       4.144824959099999  5.3929132817
O 3.9456232970000005  3.6736213510000013 4.154876766399999
O 1.9351215704999998  5.776588453800002  2.3576057410000004
O 1.1182186447000002  2.984068958500001  0.5597043610000001
O 3.9457913174000008  4.616078901500002  1.237976828999999
O 1.1181117141        5.305796430500002  4.8334310334
O 1.9348490245        2.5127136278000006 3.035570217399999
&END COORD
&KIND Si
BASIS_SET DZVP-GTH-PBE
POTENTIAL GTH-PBE-q4
&END KIND
&KIND O
BASIS_SET DZVP-GTH-PBE
POTENTIAL GTH-PBE-q6
&END KIND
&KIND H
BASIS_SET DZVP-GTH-PBE
POTENTIAL GTH-PBE-q1
&END KIND
&TOPOLOGY
CENTER_COORDINATES T
&DUMP_PDB
&END
MULTIPLE_UNIT_CELL 1 1 1
&END TOPOLOGY
&END SUBSYS
&END FORCE_EVAL
&GLOBAL
PROJECT SiO-Cell
RUN_TYPE CELL_OPT
PRINT_LEVEL MEDIUM
&END GLOBAL
&MOTION
&GEO_OPT
MAX_ITER 200
OPTIMIZER BFGS
MAX_FORCE 5.0E-5
&END GEO_OPT
&CELL_OPT
EXTERNAL_PRESSURE [bar] 0.0
PRESSURE_TOLERANCE 15.0
MAX_ITER 900
KEEP_ANGLES TRUE
OPTIMIZER CG
&CG
&LINE_SEARCH
TYPE 2PNT
&END LINE_SEARCH
&END CG
&END CELL_OPT
&END MOTION

thanks
Oliver
```