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exercise:basis_sets [2014/03/25 16:53] – scleliaexercises:2014_ethz_mmm:basis_sets [2020/08/21 10:15] (current) – external edit 127.0.0.1
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 In this exericse you will compare different basis sets and use them for computing the binding energy of an H2 molecule. 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: +The cp2k basis set format is described in detail [[:basis_sets|here]].
- +
-<code> +
- +
-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.... +
-    ... +
-</code> +
-\\ +
-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: +
- +
-<code> +
-      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 +
-</code> +
  
 ===== Part I: Different basis sets for H and H2 ===== ===== Part I: Different basis sets for H and H2 =====
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   &DFT   &DFT
-  LSD                                      ! Requests a spin-polarized calculation for an odd number of electrons+  LSD                                      ! Requests a spin-polarized calculation for non paired electrons
   MULTIPLICITY 2                           ! Multiplicity = 2S+1 (S= total spin momentum)   MULTIPLICITY 2                           ! Multiplicity = 2S+1 (S= total spin momentum)
     &POISSON                               ! Solver requested for non periodic calculations       &POISSON                               ! Solver requested for non periodic calculations  
       PERIODIC NONE                               PERIODIC NONE                        
-      PSOLVER  MT                          ! Type of solver+      PSOLVER  WAVELET                     ! Type of solver
     &END POISSON     &END POISSON
     &QS                                    ! Parameters needed to set up the Quickstep framework     &QS                                    ! Parameters needed to set up the Quickstep framework
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   &SUBSYS   &SUBSYS
 +    &TOPOLOGY                              ! Section used to center the molecule in the simulation box. Useful for big molecules 
 +      &CENTER_COORDINATES                  
 +      &END
 +    &END
     &CELL     &CELL
       ABC 10.0 10.0 10.0       ABC 10.0 10.0 10.0
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      &END      &END
      POTENTIAL ALL                         ! Specifes that the potential is for all electron calculations.      POTENTIAL ALL                         ! Specifes that the potential is for all electron calculations.
-     &POTENTIAL                            ! Usual all eletcron potential for H +     &POTENTIAL                            ! Usual all electron potential for H 
      1    0    0      1    0    0
      0.20000000    0      0.20000000    0
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 <code> <code>
 H 0 0 0      H 0 0 0     
-H 0.8 0 0   +H 0.75 0 0   
 </code> </code>
  
-<note important> The H2 molecule has an even number of electrons. Remember to take out the LSD and MULTIPLICITY keywords. </note>+<note important> The H2 molecule does not have unpaired electrons. Remember to take out the LSD and MULTIPLICITY keywords. </note>
  
 ===== Part II: Estimate the binding energy of H2 ===== ===== Part II: Estimate the binding energy of H2 =====
  
 Binding energy: \\  Binding energy: \\ 
-{{ :exercise:ppp.jpg?300 |}} 
  
 +∑Eproducts−∑Erectants=E(H2)−2⋅E(H)
  
 <note important> The binding energy value is significant only if the same basis is used for both reactants and products. </note> <note important> The binding energy value is significant only if the same basis is used for both reactants and products. </note>
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 ===== Part III: Questions ===== ===== Part III: Questions =====
  
-1.1- Report two self-made basis sets and the corresponding H energy.  +- What is the effect of:\\
- +
-1.2- What is the effect of:\\+
   * increasing/decreasing the value of the exponents for the given basis?   * increasing/decreasing the value of the exponents for the given basis?
   * adding sets with p,d symmetry to the basis? You have the same effect in H and H2?   * adding sets with p,d symmetry to the basis? You have the same effect in H and H2?
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