Exercises on basis set generation
Download
1 / 17

Javier Junquera - PowerPoint PPT Presentation


  • 99 Views
  • Uploaded on

Exercises on basis set generation Full control on the definition of the basis set functions: the PAO.Basis block. Javier Junquera. The PAO.Basis block Full control on the definition of the basis set. Species label :

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Javier Junquera' - faunus


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Exercises on basis set generation

Full control on the definition of the basis set functions:

the PAO.Basis block

Javier Junquera


The PAO.Basis block

Full control on the definition of the basis set

Specieslabel:

determines thespeciesindexaccordingtothe block ChemicalSpecieslabel


The PAO.Basis block

Full control on the definition of the basis set

Numberof shells of orbitalswithdifferent angular momentumforthecorrespondingchemicalspecies


The PAO.Basis block

Full control on the definition of the basis set

As manyshells as indicatedhere


The PAO.Basis block

Full control on the definition of the basis set


The PAO.Basis block

Full control on the definition of the basis set

Kind of basis set generationprocedure.

Default:

PAO.BasisType Split

(seethelectureontheSplitNorm)


Schemes to generate multiple- basis setsUse pseudopotential eigenfunctions with increasing number of nodes

Advantages

Orthogonal

Asymptotically complete

Disadvantages

Excited states of the pseudopotentials, usually unbound

Efficient depends on localization radii

Availables in Siesta:

PAO.BasisType Nodes

T. Ozaki et al., Phys. Rev. B 69, 195113 (2004)

http://www.openmx-square.org/


The PAO.Basis block

Full control on the definition of the basis set

Onlyusedforthegeneration of thebasis set

Default value 0.0 electrons


Solving the Schrödinger equation for an ion for the generation of the basis set

Extra charge Q

Orbitals in anions tend to be more delocalized

Orbitals in cations tend to be more localized

(For instance, this parameter might be important in some oxides)


The generation of the basis setPAO.Basis block

Full control on the definition of the basis set

Thisflag determines whetherthesoft-confinementpotentialisused

Default value: 0.0 Ry

Default value: 0.0 Bohr

Ifnegative, computed as thegivenfraction of the PAO cutoffradius.


Soft generation of the basis set-confinement potential

Available in SIESTA

J. Junquera et al., Phys. Rev. B 64, 235111 (2001)

Prefactor of thesoft-confinementpotential

Innerradiuswheretheshoft-confinementpotentialstarts off

Advantages: orbital continuous with all the derivatives continuous

diverges at rc(orbital exactly vanishes there)

zero at the core region


The generation of the basis setPAO.Basis block

Full control on the definition of the basis set

As manycolumns as zetas in theshell

Cutoffradius of ech zeta for a givenshell ( in Bohr)


The numerical atomic orbitals are strictly localized: they are zero beyond a given cutoff radius

Thisisthecutoffthatmight be explicitlyincluded in thePAO.Basis block


The are zero beyond a given cutoff radiusPAO.Basis block

Full control on the definition of the basis set

Ifsome of these are zero, thenthePAO.EnergyShiftorPAO.SplitNormwill be usedto determine thecutoff

Forthesecon-zeta onwards, ifsome of these are negative, thenthe actual rcusedwill be thegivenfraction of thefirst


The are zero beyond a given cutoff radiusPAO.Basis block

Full control on the definition of the basis set

As manycolumns as zetas in theshell

Constraint factor of each zeta.

Default value 1.0


The are zero beyond a given cutoff radiusPAO.Basis block

Full control on the definition of the basis set

A shell of polarizationfunctions (with angular momentuml+1) will be constructedfromthefirst-zeta of angular mometuml

(Default value: blank no polarizationorbitals)

Number of zetas of thepolarizationshell


The are zero beyond a given cutoff radiusPAO.Basis block

Full control on the definition of the basis set

Ifthisflagis set to S, thefollowingnumbers sets thesplit-normparameterforthatshell

Split NormParameterfortheshell


ad