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exercises:2017_ethz_mmm:reaction_energy [2017/02/22 10:01] (current)
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 +====== Reaction Energy ======
 +In this exercise, you will calculate the reaction energy for the **methane combustion** reaction:
 +\[ CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O \]
 +
 +Reaction energy:
 +\[ \sum E_\text{products} -  \sum E_\text{rectants} = \left (2\cdot E_{H_2O} + E_{CO_2} \right) - \left(E_{CH_4} + 2\cdot E_{O_2}\right) \]
 +
 +
 +Ground state oxygen, O$_2$, is a triplet diradical, a property which can explain why liquid oxygen is paramagnetic and attracted to the poles of a magnet. ​
 +{{ o3.png?600 |
 +}}
 +
 +For this reason, to get the energy of the O$_2$ molecule, a LSD calculation is required.
 +
 +===== 1.Step =====
 +
 +Run a single point calculation for CH$_4$, using the given input file. 
 +Note that the file contains explicit basis sets and potential for all-electron calculations. An explanation of the basis set formats is given here: [[basis_sets|Basis Sets]]
 +
 +<code - CH4.inp >
 +&GLOBAL
 +  PROJECT CH4
 +  RUN_TYPE ENERGY
 +  PRINT_LEVEL MEDIUM
 +&END GLOBAL
 +
 +&​FORCE_EVAL
 +  METHOD Quickstep ​             ! Electronic structure method (DFT,...)
 +  &DFT
 +    &​POISSON ​                   ! Solver requested for non periodic calculations
 +      PERIODIC NONE
 +      PSOLVER ​ WAVELET ​         ! Type of solver
 +    &END POISSON
 +    &​QS ​                        ! Parameters needed to set up the Quickstep framework
 +      METHOD GAPW               ! Method: gaussian and augmented plane waves 
 +    &END QS
 +
 +    &​XC ​                       ! Parametes needed to compute the electronic exchange potential ​
 +      &​XC_FUNCTIONAL NONE      ! No xc functional
 +      &END XC_FUNCTIONAL
 +      &​HF ​                     ! Hartree Fock exchange. In this case is 100% (no fraction specified). ​  
 +        &​SCREENING ​            ! Screening of the electronic repulsion up to the given threshold. ​              
 +          EPS_SCHWARZ 1.0E-10 ​ ! Threshold specification
 +        &END SCREENING
 +      &END HF
 +    &END XC
 +  &END DFT
 +
 +  &SUBSYS
 +    &CELL
 +      ABC 10 10 10
 +      PERIODIC NONE              ! Non periodic calculations. That's why the POISSON section is needed ​
 +    &END CELL
 +    &​TOPOLOGY ​                   ! Section used to center the atomic coordinates in the given box. Useful for big molecules
 +      &​CENTER_COORDINATES
 +      &END
 +    &END
 +    &COORD
 +  C         ​4.6425962273 ​       5.0574874650 ​       5.2069537560
 +  H         ​5.7240587065 ​       5.0555482951 ​       5.2189766147
 +  H         ​4.2766068912 ​       5.8773176685 ​       5.8100567767
 +  H         ​4.2759350196 ​       4.1226994019 ​       5.6087492584
 +  H         ​4.2938562590 ​       5.1744089096 ​       4.1899119266
 +    &END COORD
 +    &KIND H                                      ! potential and basis for H 
 +      &​BASIS ​  
 +        3
 +  1  0  0  3  1
 +         ​12.25200000 ​         0.02282200
 +          1.86870000 ​         0.15564000
 +          0.41821000 ​         0.48898000
 +  1  0  0  1  1
 +          0.10610000 ​         1.00000000
 +  1  1  1  1  1
 +          1.00000000 ​         1.00000000
 +      &​END ​                     ​
 +      POTENTIAL ALL
 +      &​POTENTIAL
 +       ​1 ​   0    0
 +       ​0.20000000 ​   0
 +      &​END ​
 +    &END KIND
 +    &KIND C                                      ! potential and basis for C
 +      &BASIS
 +         5
 +  1  0  0  6  2
 +       ​1252.60000000 ​         0.00557360 ​         0.00000000
 +        188.57000000 ​         0.04149600 ​        ​-0.00027440
 +         ​42.83900000 ​         0.18263000 ​        ​-0.00255830
 +         ​11.81800000 ​         0.46129000 ​        ​-0.03337500
 +          3.55670000 ​         0.44931000 ​        ​-0.08730500
 +          0.54258000 ​         0.00000000 ​         0.53415000
 +  1  0  0  1  1
 +          0.16058000 ​         1.00000000
 +  1  1  1  3  1
 +          9.14260000 ​         0.04449900
 +          1.92980000 ​         0.23108000
 +          0.52522000 ​         0.51227000
 +  1  1  1  1  1
 +          0.13608000 ​         1.00000000
 +  1  2  2  1  1
 +          0.80000000 ​         1.00000000
 +      &END
 +      POTENTIAL ALL
 +      &​POTENTIAL
 +      4    2    0
 +      0.34883045 ​   0
 +      &END
 +    &END KIND
 +
 +  &END SUBSYS
 +&END FORCE_EVAL
 +</​code>​
 +
 +If the calculation was performed correctly, the total energy of the CH$_4$ molecule is printed in the output file.
 +
 +<​code>​
 +  **** **** ****** ​ **  PROGRAM STARTED AT               
 + ***** ** ***  *** **   ​PROGRAM STARTED ON                   
 + ​** ​   ****   ​****** ​   PROGRAM STARTED BY                               
 + ***** **    ** ** **   ​PROGRAM PROCESS ID                                 
 +  **** **  ******* ​ **  PROGRAM STARTED IN                    ​
 +
 +.....
 +
 +ENERGY| Total FORCE_EVAL ( QS ) energy (a.u.): ​
 +
 +.....
 +
 +  **** **** ****** ​ **  PROGRAM ENDED AT                 
 + ***** ** ***  *** **   ​PROGRAM RAN ON                       
 + ​** ​   ****   ​****** ​   PROGRAM RAN BY                                  ​
 + ***** **    ** ** **   ​PROGRAM PROCESS ID                                 
 +  **** **  ******* ​ **  PROGRAM STOPPED IN
 +</​code>​
 +
 +
 +===== 2.Step =====
 +
 +Modify the input in order to perform the same calculation for:
 +  * H$_2$O
 +  * CO$_2$
 +  * O$_2$ triplet
 +
 +<note tip> Atomic coordinates for all the molecules, POTENTIAL and BASIS SET for KIND O are given at the end of the exercise. </​note>​
 +<note important>​Remember that the O2 ground state is a triplet state, with non paired electrons.
 + ​MULTIPLICITY=2S+1=3. </​note>​
 +
 +For O2 triplet, the LSD and MULTIPLICITY keywords are needed in the DFT section:
 +
 +<​code>​
 +  METHOD Quickstep ​             ​
 +   &​DFT ​                         ​
 +     ​LSD ​                          ! Requests a spin-polarized calculation for unpaired electrons
 +     ​MULTIPLICITY 3                ! Multiplicity = 2S+1 (S= total spin momentum) ​                     ​
 +  ...
 +</​code>​
 +
 +Another example can be found here [[basis_sets|Basis Sets]]
 +
 +===== 3.Step =====
 +At the end, you should get a table like:
 +
 +^ Species ^ Total Energy ^
 +| CH$_4$ ​ | ...          |
 +| O$_2$   | ...          |
 +| H$_2$O ​ | ...          |
 +| CO$_2$ ​ | ...          |
 +
 +Now you can compute the overall reaction energy. ​
 +
 +===== Questions =====
 +  - What are the total energies of O$_2$, H$_2$O, CO$_2$, and CH$_4$?
 +  - What is the overall reaction energy of the CH$_4$ combustion?
 +  - **(Optional)** What is the total energy difference between the O$_2$ singlet and triplet state?
 +
 +===== Appendix =====
 +
 +==== Basis Set for Oxygen ====
 +<​code>​
 +#O  pc-1
 +  5
 +  1  0  0  6  2
 +       ​2306.70000000 ​         0.00539400 ​         0.00000000
 +        347.15000000 ​         0.04024800 ​        ​-0.00031692
 +         ​78.89000000 ​         0.17921000 ​        ​-0.00259440
 +         ​21.87600000 ​         0.45978000 ​        ​-0.03624100
 +          6.66460000 ​         0.45234000 ​        ​-0.08779000
 +          1.06690000 ​         0.00000000 ​         0.53320000
 +  1  0  0  1  1
 +          0.30700000 ​         1.00000000
 +  1  1  1  3  1
 +         ​17.02200000 ​         0.04891900
 +          3.68380000 ​         0.24962000
 +          0.99234000 ​         0.51347000
 +  1  1  1  1  1
 +          0.24487000 ​         1.00000000
 +  1  2  2  1  1
 +          1.00000000 ​         1.00000000
 +</​code>​
 +
 +==== Potential for Oxygen ====
 +<​code>​
 +#O ALLELECTRON ALL
 +    4    4    0
 +     ​0.24762086 ​   0
 +</​code>​
 +
 +==== Coordinates for O$_2$ ====
 +<​code>​
 +O         ​4.4720538104 ​       4.7584649515 ​       4.9999999998
 +O         ​5.5279461896 ​       5.2415350485 ​       4.9999999995
 +</​code>​
 +
 +==== Coordinates for CO$_2$ ====
 +<​code>​
 +  C         ​4.9999776408 ​       4.9999662056 ​       4.9999894728
 +  O         ​5.6486993295 ​       5.9339540261 ​       5.0004691016
 +  O         ​4.3512530072 ​       4.0659797648 ​       4.9995464311
 +</​code>​
 +
 +==== Coordinates for H$_2$O ====
 +<​code>​
 +  O         ​4.6926974603 ​       4.7525411835 ​       4.6307067609
 +  H         ​5.6350172910 ​       4.8022721035 ​       4.7052454388
 +  H         ​4.3528571397 ​       5.2445222023 ​       5.3644975249
 +</​code>​
  
exercises/2017_ethz_mmm/reaction_energy.txt ยท Last modified: 2017/02/22 10:01 (external edit)