exercises:2014_ethz_mmm:basis_sets
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exercises:2014_ethz_mmm:basis_sets [2014/03/25 16:53] sclelia |
exercises:2014_ethz_mmm:basis_sets [2014/10/15 12:37] (current) oschuett exercise:basis_sets renamed to exercise:2014_ethz_mmm:basis_sets |
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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 ===== | ||
| Line 53: | Line 21: | ||
| | | ||
| &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 | ||
| Line 74: | Line 42: | ||
| | | ||
| &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 | ||
| Line 90: | Line 62: | ||
| &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 | ||
| Line 121: | Line 93: | ||
| <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 |}} | ||
| + | \[ \sum E_\text{products} - \sum E_\text{rectants} = E(H_2) - 2 \cdot E(H) \] | ||
| <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> | ||
| Line 149: | Line 121: | ||
| ===== 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? | ||
exercises/2014_ethz_mmm/basis_sets.1395766419.txt.gz · Last modified: 2014/03/25 16:53 by sclelia
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