exercises:2014_ethz_mmm:basis_sets
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exercise:basis_sets [2014/03/25 13:02] – sclelia | exercise:2014_ethz_mmm:basis_sets [2014/10/15 12:37] – exercise:basis_sets renamed to exercise:2014_ethz_mmm:basis_sets oschuett | ||
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====== Basis Sets ====== | ====== Basis Sets ====== | ||
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]]. |
- | < | + | ===== Part I: Different basis sets for H and H2 ===== |
+ | ==== 1.Step ==== | ||
+ | |||
+ | Run a calculation with the following input file. Comment lines are marked with ! | ||
+ | |||
+ | < | ||
+ | |||
+ | & | ||
+ | PROJECT H-mybasis | ||
+ | RUN_TYPE ENERGY | ||
+ | &END GLOBAL | ||
+ | |||
+ | & | ||
+ | METHOD Quickstep | ||
+ | |||
+ | &DFT | ||
+ | LSD ! Requests a spin-polarized calculation for non paired electrons | ||
+ | MULTIPLICITY 2 ! Multiplicity = 2S+1 (S= total spin momentum) | ||
+ | & | ||
+ | PERIODIC NONE | ||
+ | PSOLVER | ||
+ | &END POISSON | ||
+ | & | ||
+ | METHOD GAPW ! Method: gaussian and augmented plane waves | ||
+ | &END QS | ||
+ | & | ||
+ | & | ||
+ | &END XC_FUNCTIONAL | ||
+ | & | ||
+ | & | ||
+ | EPS_SCHWARZ 1.0E-10 | ||
+ | &END SCREENING | ||
+ | &END HF | ||
+ | &END XC | ||
+ | &END DFT | ||
+ | |||
+ | & | ||
+ | & | ||
+ | & | ||
+ | &END | ||
+ | &END | ||
+ | &CELL | ||
+ | ABC 10.0 10.0 10.0 | ||
+ | PERIODIC NONE ! Non periodic calculations. That's why the POISSON scetion is needed | ||
+ | &END CELL | ||
+ | & | ||
+ | | ||
+ | &END COORD | ||
+ | &KIND H | ||
+ | & | ||
+ | 2 | ||
+ | 1 0 0 1 1 | ||
+ | 0.35 1 | ||
+ | 1 0 0 1 1 | ||
+ | 0.6 1 | ||
+ | & | ||
+ | | ||
+ | & | ||
+ | | ||
+ | | ||
+ | & | ||
+ | &END KIND | ||
+ | &END SUBSYS | ||
+ | &END FORCE_EVAL | ||
- | 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.Step ==== |
+ | Try to change the basis set, and report the obtained energy values for H. | ||
+ | After a couple of tries on your own, try to use some of the literature basis sets (given at the end of this exercise). | ||
+ | At the end, you should get a table like this : | ||
+ | |||
+ | ^ Basis set ^ Energy | ||
+ | | mybasis (from given input) | ||
+ | | basis try 1 | .... | | ||
+ | | basis try 2 | .... | | ||
+ | | .... | .... | | ||
+ | | pc-0 | .... | | ||
+ | | pc-1 | .... | | ||
+ | | pc-2 | .... | | ||
+ | |||
+ | <note tip>Is always good to keep record of self-created basis sets, to track the effect of a change in value and number of exponents, contractions....etc.. </ | ||
+ | |||
+ | Repeat the procedure for H2. \\ | ||
+ | H2 coordinates: | ||
< | < | ||
- | 2 2 Sets | + | H 0 0 0 |
- | 1 0 0 1 1 Set 1: lmin=0 ; lmax=0 (→ s functions!) ; 1 exponent ; 1 contraction | + | H 0.75 0 0 |
- | 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 | + | |
- | | + | |
</ | </ | ||
+ | |||
+ | <note important> | ||
+ | |||
+ | ===== Part II: Estimate the binding energy of H2 ===== | ||
+ | |||
+ | Binding energy: \\ | ||
+ | |||
+ | \[ \sum E_\text{products} - \sum E_\text{rectants} = E(H_2) - 2 \cdot E(H) \] | ||
+ | |||
+ | <note important> | ||
+ | |||
+ | |||
+ | You can now update your table: | ||
+ | |||
+ | ^ Basis set ^ Energy | ||
+ | | mybasis (from given input) | ||
+ | | basis try 1 | .... | .... | .... | | ||
+ | | basis try 2 | .... | .... | .... | | ||
+ | | .... | .... | .... | .... | | ||
+ | | pc-0 | .... | .... | .... | | ||
+ | | pc-1 | .... | .... | .... | | ||
+ | | pc-2 | .... | .... | .... | | ||
+ | | .... | .... | .... | .... | | ||
+ | |||
+ | ===== Part III: Questions ===== | ||
+ | |||
+ | - What is the effect of:\\ | ||
+ | * increasing/ | ||
+ | * adding sets with p,d symmetry to the basis? You have the same effect in H and H2? | ||
+ | |||
+ | |||
+ | ===== Part IV: Additional basis sets ===== | ||
+ | |||
+ | |||
+ | |||
+ | H pc-0 | ||
+ | 2 | ||
+ | 1 0 0 2 1 | ||
+ | 4.34480000 | ||
+ | 0.66049000 | ||
+ | 1 0 0 1 1 | ||
+ | 0.13669000 | ||
+ | |||
+ | H pc-1 | ||
+ | 3 | ||
+ | 1 0 0 3 1 | ||
+ | | ||
+ | 1.86870000 | ||
+ | 0.41821000 | ||
+ | 1 0 0 1 1 | ||
+ | 0.10610000 | ||
+ | 1 1 1 1 1 | ||
+ | 1.00000000 | ||
+ | |||
+ | H pc-2 | ||
+ | 6 | ||
+ | 1 0 0 4 1 | ||
+ | | ||
+ | | ||
+ | 2.59930000 | ||
+ | 0.73513000 | ||
+ | 1 0 0 1 1 | ||
+ | 0.23167000 | ||
+ | 1 0 0 1 1 | ||
+ | 0.07414700 | ||
+ | 1 1 1 1 1 | ||
+ | 1.60000000 | ||
+ | 1 1 1 1 1 | ||
+ | 0.45000000 | ||
+ | 1 2 2 1 1 | ||
+ | 1.25000000 | ||
+ | |||
+ | |||
- | ===== Part I: ===== | ||
exercises/2014_ethz_mmm/basis_sets.txt · Last modified: 2020/08/21 10:15 by 127.0.0.1