Sorry for the way I asked the question....
Thanks for your reply....well I checked the geometry in Xcrysden and it
showed the correct picture(if I replicate the picture in all directions) .
Actually apart from this , I calculated the energies of the slabs extending
upto infinity in 2 directions and restricted in the z direction by giving a
big vacuum space in the unit cell(I guess this is the cluster you are
talking about). I used Ni infinite slabs, then i used Ni infinite slabs with
adatoms and calculated the enery differences and the differences were like
10KeV!
Well in this case, I had put a big vacuum space in all the 3 directions
and it says that virtual memory is not enough
InitMesh: MESH = 500 x 500 x 500 = 125000000
InitMesh: Mesh cutoff (required, used) = 100.000 104.475 Ry
forrtl: severe (41): insufficient virtual memory
On Wed, Jul 14, 2010 at 1:10 PM, N H <[email protected]> wrote:
> Did you checked the output geometry to see whether this is really the
> geometry you want or not?
>
> Another question: Do you like to calculate a Slab or a cluster? It seems
> that your calculation is set to a Cluster.
>
> It is also not clear which energy you would like to calculate. Remember
> that absolute total energies calculated with SIESTA ( or any other method )
> have no meaning in itself - once the energy reference is arbitrary. You have
> to compare it with the energy of another well-defined system
> and establish energy differences.
>
> Just to give an idea, I calculate ZnO slabs with more or less 40 atoms (
> including some molecules adsorbed ) and the total energies are something
> like -35KeV ... and it is normal.
>
> A last tip: The people here in this list use to be very friendly and
> helpful. So there is no need to urging someone to solve the problem you
> posted with "It's very urgent!!". Everybody here is open to help each other,
> but everybody here also have urgent stuff to do besides answering the SIESTA
> mail-L. If you want help, please ask it nicely.
>
> Best Regards
>
>
> NH
>
>
>
>
> On Wed, Jul 14, 2010 at 12:01 PM, Juan Beltran <[email protected]
> > wrote:
>
>> I find that your system do not have that many C atoms, how does the energy
>> compare with a pure Ni system?, still large?. Compare also the energy you
>> obtain for that big supercell with the pure FCC Ni system (1 atom may do).
>> The difference should be due to the presence of vacum along the three
>> directions and I guess it should be less that 100eV from the 50KeV you
>> obtain from the large system.
>>
>> Juan
>>
>> On 07/14/2010 12:45 AM, tarang mungole wrote:
>>
>>> I have made a slab with FCC configuration and I want to calculate the
>>> energy of the slab!! The slab contains 5 layers of Nickel atoms and a carbon
>>> atom on the top of it. I just want to calculate the energy of this system!!!
>>> ....I made a supercell having 5X5X5 lattice constants in each direction ( 5a
>>> 5a 5a 60 60 60) and then gave a BIG vaccum space so that the nearby
>>> Replicated supercells do not interact.(Is this a correct concept??????) .
>>> The problem is that the energies that i get are very large!!!! about
>>> -50KeV!! Can any body tell what is wrong in my fdf input file....it's very
>>> urgent!!
>>>
>>> ---------------------------------------------------FDF
>>> FILE----------------------------------------------------------------------------------------------------------------------------------------------
>>>
>>> %block ChemicalSpeciesLabel
>>> 1 28 Ni
>>> 2 6 C
>>> %endblock ChemicalSpeciesLabel
>>>
>>> SaveRho .true.
>>>
>>> LatticeConstant 1.0 Ang
>>>
>>> %block LatticeParameters
>>> 99.6 99.6 99.6 60. 60. 60.
>>> %endblock LatticeParameters
>>>
>>> %block AtomicCoordinatesOrigin
>>> 0.000 0.000 0.000
>>> %endblock AtomicCoordinatesOrigin
>>>
>>>
>>>
>>> MD.TypeOfRun CG
>>> MD.NumCGSteps 0
>>>
>>> AtomicCoordinatesFormat Fractional
>>>
>>> %block AtomicCoordinatesAndAtomicSpecies
>>> 0.000 0.000 0.000 1
>>> 0.025 0.000 0.000 1
>>> 0.050 0.000 0.000 1
>>> 0.075 0.000 0.000 1
>>> 0.000 0.025 0.000 1
>>> 0.025 0.025 0.000 1
>>> 0.050 0.025 0.000 1
>>> 0.075 0.025 0.000 1
>>> 0.000 0.050 0.000 1
>>> 0.025 0.050 0.000 1
>>> 0.050 0.050 0.000 1
>>> 0.075 0.050 0.000 1
>>> 0.000 0.075 0.000 1
>>> 0.025 0.075 0.000 1
>>> 0.050 0.075 0.000 1
>>> 0.075 0.075 0.000 1
>>> 0.000 0.000 0.025 1
>>> 0.025 0.000 0.025 1
>>> 0.050 0.000 0.025 1
>>> 0.075 0.000 0.025 1
>>> 0.000 0.025 0.025 1
>>> 0.025 0.025 0.025 1
>>> 0.050 0.025 0.025 1
>>> 0.075 0.025 0.025 1
>>> 0.000 0.050 0.025 1
>>> 0.025 0.050 0.025 1
>>> 0.050 0.050 0.025 1
>>> 0.075 0.050 0.025 1
>>> 0.000 0.075 0.025 1
>>> 0.025 0.075 0.025 1
>>> 0.050 0.075 0.025 1
>>> 0.075 0.075 0.025 1
>>> 0.000 0.000 0.050 1
>>> 0.025 0.000 0.050 1
>>> 0.050 0.000 0.050 1
>>> 0.075 0.000 0.050 1
>>> 0.000 0.025 0.050 1
>>> 0.025 0.025 0.050 1
>>> 0.050 0.025 0.050 1
>>> 0.075 0.025 0.050 1
>>> 0.000 0.050 0.050 1
>>> 0.025 0.050 0.050 1
>>> 0.050 0.050 0.050 1
>>> 0.075 0.050 0.050 1
>>> 0.000 0.075 0.050 1
>>> 0.025 0.075 0.050 1
>>> 0.050 0.075 0.050 1
>>> 0.075 0.075 0.050 1
>>> 0.000 0.000 0.075 1
>>> 0.025 0.000 0.075 1
>>> 0.050 0.000 0.075 1
>>> 0.075 0.000 0.075 1
>>> 0.000 0.025 0.075 1
>>> 0.025 0.025 0.075 1
>>> 0.050 0.025 0.075 1
>>> 0.075 0.025 0.075 1
>>> 0.000 0.050 0.075 1
>>> 0.025 0.050 0.075 1
>>> 0.050 0.050 0.075 1
>>> 0.075 0.050 0.075 1
>>> 0.000 0.075 0.075 1
>>> 0.025 0.075 0.075 1
>>> 0.050 0.075 0.075 1
>>> 0.075 0.075 0.075 1
>>> 0.000 0.000 0.100 1
>>> 0.025 0.000 0.100 1
>>> 0.050 0.000 0.100 1
>>> 0.075 0.000 0.100 1
>>> 0.000 0.025 0.100 1
>>> 0.025 0.025 0.100 1
>>> 0.050 0.025 0.100 1
>>> 0.075 0.025 0.100 1
>>> 0.000 0.050 0.100 1
>>> 0.025 0.050 0.100 1
>>> 0.050 0.050 0.100 1
>>> 0.075 0.050 0.100 1
>>> 0.000 0.075 0.100 1
>>> 0.025 0.075 0.100 1
>>> 0.050 0.075 0.100 1
>>> 0.075 0.075 0.100 1
>>> 0.033 0.033 0.125 2
>>> 0.100 0.000 0.000 1
>>> 0.100 0.025 0.000 1
>>> 0.100 0.050 0.000 1
>>> 0.100 0.075 0.000 1
>>> 0.100 0.100 0.000 1
>>> 0.100 0.000 0.025 1
>>> 0.100 0.025 0.025 1
>>> 0.100 0.050 0.025 1
>>> 0.100 0.075 0.025 1
>>> 0.100 0.100 0.025 1
>>> 0.100 0.000 0.050 1
>>> 0.100 0.025 0.050 1
>>> 0.100 0.050 0.050 1
>>> 0.100 0.075 0.050 1
>>> 0.100 0.100 0.050 1
>>> 0.100 0.000 0.075 1
>>> 0.100 0.025 0.075 1
>>> 0.100 0.050 0.075 1
>>> 0.100 0.075 0.075 1
>>> 0.100 0.100 0.075 1
>>> 0.100 0.000 0.100 1
>>> 0.100 0.025 0.100 1
>>> 0.100 0.050 0.100 1
>>> 0.100 0.075 0.100 1
>>> 0.100 0.100 0.100 1
>>> 0.000 0.100 0.000 1
>>> 0.025 0.100 0.000 1
>>> 0.050 0.100 0.000 1
>>> 0.075 0.100 0.000 1
>>> 0.000 0.100 0.025 1
>>> 0.025 0.100 0.025 1
>>> 0.050 0.100 0.025 1
>>> 0.075 0.100 0.025 1
>>> 0.000 0.100 0.050 1
>>> 0.025 0.100 0.050 1
>>> 0.050 0.100 0.050 1
>>> 0.075 0.100 0.050 1
>>> 0.000 0.100 0.075 1
>>> 0.025 0.100 0.075 1
>>> 0.050 0.100 0.075 1
>>> 0.075 0.100 0.075 1
>>> 0.000 0.100 0.100 1
>>> 0.025 0.100 0.100 1
>>> 0.050 0.100 0.100 1
>>> 0.075 0.100 0.100 1
>>> %endblock AtomicCoordinatesAndAtomicSpecies
>>>
>>> SolutionMethod diagon
>>>
>>>
>>>
>>>
>>>
>>> Thnx in advance!!
>>>
>>>
>
