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Basis Sets

In this exericse you will compare different basis sets and use them for computing the binding energy of an H2 molecule.

The cp2k basis set format is the following:

Nsets
  n1 lmin lmax Nexp Ncontr
    exp1 contr1 contr2 contr3 ...
    exp2 contr4 contr5 contr6 ...
    Nexp....
  n2 lmin lmax Nexp Ncontr
    exp1 contr1 contr2 contr3 ...
    exp2 contr4 contr5 contr6 ...
    Nexp....
    ...

Nsets = number of sets.
n1,n2… = main quantum number (but it gets ignored by the program!)
lmin = min l (angular quantum number) of the set ( s = 0 ; p = 1 ; d = 2 …)
lmax = max l (angular quantum number) of the set ( s = 0 ; p = 1 ; d = 2 …)
Nexp = number of exponents of the set
Ncontr = number of contaction coefficients per angular quantum number

As an example:

      2                 2 Sets
      1 0 0 1 1         Set 1: lmin=0 ; lmax=0 (→ s functions!) ; 1 exponent ; 1 contraction
        0.35 1          exponent1 of  set 1 ; contraction 
      1 1 1 1 1         Set 2: lmin=1 ; lmax=1 (→ p functions!) ; 1 exponenet ; 1 contraction
        0.6 1           exponent1 of set 2 ;  contraction

Part I: Create your own basis set for H

1.Step

Save the following input file. Comment lines are marked with !

mybasis.inp

 
&GLOBAL
  PROJECT H-mybasis
  RUN_TYPE ENERGY
&END GLOBAL

&FORCE_EVAL
  METHOD Quickstep                         !electronic structure method
  &DFT
    POTENTIAL_FILE_NAME ./POTENTIAL        !speciies the location of the potential file name
    LSD
    &MGRID
      CUTOFF 200
    &END MGRID
    &POISSON
      PERIODIC NONE
      PSOLVER  MT
    &END
    &QS
      METHOD GAPW
    &END QS
    &SCF
      EPS_SCF 1.0E-6
      SCF_GUESS ATOMIC
    &END SCF
    &XC
      &XC_FUNCTIONAL NONE
      &END XC_FUNCTIONAL
      &HF
        &SCREENING
          EPS_SCHWARZ 1.0E-10
        &END
        &MEMORY
          MAX_MEMORY  100
        &END
      &END
    &END XC
  &END DFT
  &SUBSYS
    &CELL
      ABC 10.0 10.0 10.0
      PERIODIC NONE
    &END CELL
    &COORD
     H   0.0 0.0 0.0
    &END COORD
    &KIND H
     &BASIS
     2
     1 0 0 1 1
     0.35 1
     1 0 0 1 1
     0.6 1
     &END
     POTENTIAL ALL
    &END KIND
  &END SUBSYS
&END FORCE_EVAL