165. Approach to computing reorganisational energies using nwchem

I set out to reproduce Malagoli and Brédas in Chemical Physics Letter, 2000, 327, 13-17 (Link). Essentially it's a paper on calculating reorganisational energies in a few simple organic species, such as biphenyl.  I've already covered this work to some extent (here: http://verahill.blogspot.com.au/2012/05/dft-gridsize-ecce-defaults-to-medium.html ) but here's a step-by-step walkthrough and nwchem:

Approach (using biphenyl):
1. Draw biphenyl -- the dihedral angle between the two rings should be about 38 degrees
2. Optimize structure using b3lyp/6-31+g in gas phase. Gives you E1
3. Change the charge and multiplicity to +1 and 2, respectively.
4. Calculate single-point energy using the previously optimised structure (from step 2, i.e. don't optimise). Gives E2.
5. Now, optimise structure. Gives E3.
6. Change the charge and multiplicity to 0 and 1. Calculate single point energy of the optimised structure in step 5. Gives E4.
7. ΔE=(E2-E3)+(E4-E1). Convert energies from Hartree to eV by multiplying by 27.2107

---

Using nwchem:

title "Calculating E1"
start neutral_ground_state
geometry
 C     3.58691     -1.70661e-06     0.000280946
 C     2.87790     -0.739281     0.946515
 C     1.48493     -0.738173     0.945097
 C     0.747197     0.00000     0.000278762
 C     1.48488     0.738183     -0.944553
 C     2.87785     0.739273     -0.945948
 C     -0.747197     0.00000     0.000278762
 C     -1.48488     0.00000     -1.19873
 C     -2.87785     0.00000     -1.20050
 C     -1.48493     0.00000     1.19927
 C     -3.58691     0.00000     0.000281534
 C     -2.87790     0.00000     1.20107
 H     4.67272     9.42775e-05     0.000158092
 H     3.40921     -1.32260     1.69312
 H     0.975305     -1.32691     1.69865
 H     3.40931     1.32254     -1.69249
 H     -3.40931     0.00000     -2.14788
 H     -0.975305     0.00000     2.15554
 H     -4.67272     0.00000     0.000125630
 H     -3.40921     0.00000     2.14853
 H     -0.975288     0.00000     -2.15502
 H     0.975288     1.32693     -1.69812
end
charge 0
basis "ao basis" cartesian print
  H library "6-31G**"
  C library "6-31G**"
end
dft
    direct
    grid fine
    xc b3lyp
    mult 1
end
task dft optimize

and

title "Calculating E2"
start cation_excited_state
geometry units angstrom
 C     0.00000     -3.56301     0.00000
 C     -1.13927     -2.85928     -0.393841
 C     -1.13879     -1.46545     -0.394153
 C     0.00000     -0.742814     0.00000
 C     1.13879     -1.46545     0.394153
 C     1.13927     -2.85928     0.393841
 C     0.00000     0.742814     0.00000
 C     1.13879     1.46545     -0.394153
 C     1.13927     2.85928     -0.393841
 C     -1.13879     1.46545     0.394153
 C     0.00000     3.56301     0.00000
 C     -1.13927     2.85928     0.393841
 H     0.00000     -4.64896     0.00000
 H     -2.02827     -3.39662     -0.711607
 H     -2.02148     -0.928265     -0.727933
 H     2.02827     -3.39662     0.711607
 H     2.02827     3.39662     -0.711607
 H     -2.02148     0.928265     0.727933
 H     0.00000     4.64896     0.00000
 H     -2.02827     3.39662     0.711607
 H     2.02148     0.928265     -0.727933
 H     2.02148     -0.928265     0.727933
end
charge 1
basis "ao basis" cartesian print
  H library "6-31G**"
  C library "6-31G**"
end
dft
    direct
    grid fine
    xc b3lyp
    mult 2
end
task dft energy

and

title "Calculating E3"
start cation_ground_state
geometry units angstrom
 C     0.00000     -3.56301     0.00000
 C     -1.13927     -2.85928     -0.393841
 C     -1.13879     -1.46545     -0.394153
 C     0.00000     -0.742814     0.00000
 C     1.13879     -1.46545     0.394153
 C     1.13927     -2.85928     0.393841
 C     0.00000     0.742814     0.00000
 C     1.13879     1.46545     -0.394153
 C     1.13927     2.85928     -0.393841
 C     -1.13879     1.46545     0.394153
 C     0.00000     3.56301     0.00000
 C     -1.13927     2.85928     0.393841
 H     0.00000     -4.64896     0.00000
 H     -2.02827     -3.39662     -0.711607
 H     -2.02148     -0.928265     -0.727933
 H     2.02827     -3.39662     0.711607
 H     2.02827     3.39662     -0.711607
 H     -2.02148     0.928265     0.727933
 H     0.00000     4.64896     0.00000
 H     -2.02827     3.39662     0.711607
 H     2.02148     0.928265     -0.727933
 H     2.02148     -0.928265     0.727933
end
charge 1
basis "ao basis" cartesian print
  H library "6-31G**"
  C library "6-31G**"
end
dft
    direct
    grid fine
    xc b3lyp
    mult 2
end
task dft optimize

and

title "Calculating E4"
start neutral_excited_state
geometry
 C     0.00000     -3.54034     0.00000
 C     -1.20296     -2.84049     -0.216000
 C     -1.20944     -1.46171     -0.206253
 C     0.00000     -0.721866     0.00000
 C     1.20944     -1.46171     0.206253
 C     1.20296     -2.84049     0.216000
 C     0.00000     0.721866     0.00000
 C     1.20944     1.46171     -0.206253
 C     1.20296     2.84049     -0.216000
 C     -1.20944     1.46171     0.206253
 C     0.00000     3.54034     0.00000
 C     -1.20296     2.84049     0.216000
 H     0.00000     -4.62590     0.00000
 H     -2.12200     -3.38761     -0.395378
 H     -2.13673     -0.938003     -0.401924
 H     2.12200     -3.38761     0.395378
 H     2.12200     3.38761     -0.395378
 H     -2.13673     0.938003     0.401924
 H     0.00000     4.62590     0.00000
 H     -2.12200     3.38761     0.395378
 H     2.13673     0.938003     -0.401924
 H     2.13673     -0.938003     0.401924
end
charge 0
basis "ao basis" cartesian print
  H library "6-31G**"
  C library "6-31G**"
end
dft
    direct
    grid fine
    xc b3lyp
    mult 1
end
task dft energy

And it all gives:

E1: Total DFT energy =     -463.321927500065
E2: Total DFT energy =     -463.035336642074
E3: Total DFT energy =     -463.042292962541
E:4 Total DFT energy =     -463.315725187090

ΔE=-463.035336642074-(-463.042292962541)+(-463.315725187090-(-463.321927500065))=0.013158633442Hartree= .3580556270002294 eV ≅ 0.36 eV i.e. the same as the paper.