SCF Methods

[Hepsibahpriyadarshini C]

Which SCF method is best for studying Ag₂O.. I have this doubt since OT does'nt support K-Points though it converges faster. Can someone please clarify.

Regards

C.Hepsibah

[Patrick Gono]

Dear Hepsibah,

If you are not using k-points, make sure that your results are converged with respect to the super-cell size. You can use the MULTIPLE_UNIT_CELL keywords in your &CELL and &TOPOLOGY sections.

As Ag2O is metallic under GGA functionals, you might eventually encounter some difficulties with the convergence when using OT. If you do, switch to KPOINTS instead.

Yours sincerely,

Patrick Gono

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[Hepsibahpriyadarshini C]

I'll try it out Patrick.. So If I'll have to include K-points its better that I go with Diagonalisation procedure right...

Yours sincerely,

Hepsibah.C 

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[Hepsibahpriyadarshini C]

Thank you Travis..I'll go with Diagonalisation then..

How do I calculate the cohesive energy for bulk Ag2O ?

Yours sincerely,

C.Hepsibah

On 11 Dec 2019 1:22 pm, "Travis" <polla...@gmail.com> wrote:

Hi,

OT works in specific cases like liquids and insulating solids with a large gamma point. OT is not available with kpoints. It also fails for metals and other conducting/small gap materials (whether this is a property of the material or an artifact of the functional). Compile CP2K with ELPA to accelerate calculations requiring full diagonalization by a pretty generous amount.

-T

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[Hepsibahpriyadarshini C]

Hi, 

I have carried out cell optimisation for Ag2O with OT method. I am not able to obtain convergence with diagonalisation method. Can I take the final co-ordinates generated using OT and feed it as  input for optimising the geometry. Can 2 different SCF procedures be employed.

Thank you!

On Wed, Dec 11, 2019 at 1:34 PM Hepsibahpriyadarshini C <heps...@srmist.edu.in> wrote:

Thank you Travis..I'll go with Diagonalisation then..

How do I calculate the cohesive energy for bulk Ag2O ?

Yours sincerely,

C.Hepsibah

On 11 Dec 2019 1:22 pm, "Travis" <polla...@gmail.com> wrote:

Hi,

OT works in specific cases like liquids and insulating solids with a large gamma point. OT is not available with kpoints. It also fails for metals and other conducting/small gap materials (whether this is a property of the material or an artifact of the functional). Compile CP2K with ELPA to accelerate calculations requiring full diagonalization by a pretty generous amount.

-T

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