exercises:2015_ethz_mmm:basis_sets
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exercises:2015_ethz_mmm:basis_sets [2015/04/16 14:17] – oschuett | exercises:2015_ethz_mmm:basis_sets [2015/04/16 14:27] – oschuett | ||
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====== Basis Sets ====== | ====== Basis Sets ====== | ||
- | In this exercise you will compare different basis sets and use them for computing the binding energy of an H2 molecule. | + | In this exercise you will compare different basis sets and use them for computing the binding energy of an H$_2$ molecule. |
The cp2k basis set format is described in detail [[: | The cp2k basis set format is described in detail [[: | ||
- | ===== Part I: Different basis sets for H and H2 ===== | + | ===== Part I: Different basis sets for H and H$_2$ ===== |
==== 1.Step ==== | ==== 1.Step ==== | ||
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==== 3.Step ==== | ==== 3.Step ==== | ||
- | Repeat the procedure for H2. For this you will have to add a second H atom to the coordinate section and run a geometry optimization to determine the equilibrium distance. Note that this equilibrium distance might also depend on your basis-set. | + | Repeat the procedure for H$_2$. For this you will have to add a second H atom to the coordinate section and run a geometry optimization to determine the equilibrium distance. Note that this equilibrium distance might also depend on your basis-set. |
- | <note important> | + | <note important> |
- | ===== Part II: Estimate the binding energy of H2 ===== | + | ===== Part II: Estimate the binding energy of H$_2$ ===== |
- | Binding | + | Based on the formula for the // |
\[ \sum E_\text{products} - \sum E_\text{reactants} = E(H_2) - 2 \cdot E(H) \] | \[ \sum E_\text{products} - \sum E_\text{reactants} = E(H_2) - 2 \cdot E(H) \] | ||
- | <note important> | ||
- | + | ^ Basis set ^ Energy H [$E_h$] ^ Energy | |
- | You can now update your table: | + | |
- | + | ||
- | ^ Basis set ^ Energy H [$E_h$] ^ Energy | + | |
| mybasis (from given input) | .... | .... | .... | .... | | | mybasis (from given input) | .... | .... | .... | .... | | ||
| basis try 1 | .... | .... | .... | .... | | | basis try 1 | .... | .... | .... | .... | | ||
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| pc-2 | .... | .... | .... | .... | | | pc-2 | .... | .... | .... | .... | | ||
| .... | .... | .... | .... | .... | | | .... | .... | .... | .... | .... | | ||
- | ===== Part III: Questions ===== | ||
- | - What is the effect of:\\ | + | <note important> |
- | * increasing/ | + | |
- | * adding sets with p,d symmetry to the basis? You have the same effect in H and H2? | + | |
- | + | ===== Part III: Questions | |
- | ===== Part IV: Additional basis sets ===== | + | - What is the effect of changing the exponents in a basis-set? |
+ | - What is the effect of adding p- and d-function to the basis-set? Do H and H$_2$ respond differently? | ||
+ | ===== Appendix: Literature Basis-Sets ===== | ||
+ | < | ||
H pc-0 | H pc-0 | ||
2 | 2 | ||
Line 161: | Line 157: | ||
1.25000000 | 1.25000000 | ||
- | + | </ | |
exercises/2015_ethz_mmm/basis_sets.txt · Last modified: 2020/08/21 10:15 by 127.0.0.1