Skip to main content
Chemistry

Return to Question

Became Hot Network Question
deleted 13 characters in body; edited tags; edited title
Source Link
Martin - マーチン ♦
Martin - マーチン ♦
  • 44.4k
  • 13
  • 161
  • 327

Why don't the MO energies do not sum up to Hartree-Fock SCF value?

I would like to calculate Hartree-Fock energy of H3+$\ce{H3^+}$ ion from orbital energies. So I performed the following calculation in Gaussian16Gaussian 16:

# hf/sto-3g
1 1
H                     0.        0.        0.
H                     0.        0.        0.85261
H                     0.        0.       -0.85261

Then I took these two energy values from the log:

 nuclear repulsion energy         1.5516354770 Hartrees
...
Alpha  occ. eigenvalues --   -1.07569

Unexpectedly, the sum 1.5516354770 - 2 * 1.07569 = -0.599765 Hartree is not even close to "SCF Done:" value computed by Gaussian:

SCF Done:  E(RHF) =  -1.20555771776

Since I didn't explicitly require any corrections or solvation model, I wonder what contribution to SCF energy did I miss?

Input file and log are uploaded on https://github.com/nkrivoshchapov/h3plus_calculation

Why MO energies do not sum up to Hartree-Fock SCF value?

I would like to calculate Hartree-Fock energy of H3+ ion from orbital energies. So I performed the following calculation in Gaussian16:

# hf/sto-3g
1 1
H                     0.        0.        0.
H                     0.        0.        0.85261
H                     0.        0.       -0.85261

Then I took these two energy values from the log:

 nuclear repulsion energy         1.5516354770 Hartrees
...
Alpha  occ. eigenvalues --   -1.07569

Unexpectedly, the sum 1.5516354770 - 2 * 1.07569 = -0.599765 Hartree is not even close to "SCF Done:" value computed by Gaussian:

SCF Done:  E(RHF) =  -1.20555771776

Since I didn't explicitly require any corrections or solvation model, I wonder what contribution to SCF energy did I miss?

Input file and log are uploaded on https://github.com/nkrivoshchapov/h3plus_calculation

Why don't the MO energies sum up to Hartree-Fock SCF value?

I would like to calculate Hartree-Fock energy of $\ce{H3^+}$ ion from orbital energies. So I performed the following calculation in Gaussian 16:

# hf/sto-3g
1 1
H                     0.        0.        0.
H                     0.        0.        0.85261
H                     0.        0.       -0.85261

Then I took these two energy values from the log:

 nuclear repulsion energy         1.5516354770 Hartrees
...
Alpha  occ. eigenvalues --   -1.07569

Unexpectedly, the sum 1.5516354770 - 2 * 1.07569 = -0.599765 Hartree is not even close to "SCF Done:" value computed by Gaussian:

SCF Done:  E(RHF) =  -1.20555771776

Since I didn't explicitly require any corrections or solvation model, I wonder what contribution to SCF energy did I miss?

Input file and log are uploaded on https://github.com/nkrivoshchapov/h3plus_calculation

edited tags
Link
orthocresol
orthocresol
  • 71.9k
  • 12
  • 249
  • 423
Source Link
Bobik
Bobik
  • 155
  • 4

Why MO energies do not sum up to Hartree-Fock SCF value?

I would like to calculate Hartree-Fock energy of H3+ ion from orbital energies. So I performed the following calculation in Gaussian16:

# hf/sto-3g
1 1
H                     0.        0.        0.
H                     0.        0.        0.85261
H                     0.        0.       -0.85261

Then I took these two energy values from the log:

 nuclear repulsion energy         1.5516354770 Hartrees
...
Alpha  occ. eigenvalues --   -1.07569

Unexpectedly, the sum 1.5516354770 - 2 * 1.07569 = -0.599765 Hartree is not even close to "SCF Done:" value computed by Gaussian:

SCF Done:  E(RHF) =  -1.20555771776

Since I didn't explicitly require any corrections or solvation model, I wonder what contribution to SCF energy did I miss?

Input file and log are uploaded on https://github.com/nkrivoshchapov/h3plus_calculation