return to home page Computational Chemistry Comparison and Benchmark DataBase Release 22 (May 2022) Standard Reference Database 101 National Institute of Standards and Technology
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All results from a given calculation for Si2 (Silicon diatomic)

using model chemistry: CCD/6-31+G**

19 10 17 12 22

States and conformations

State Conformation minimum conformation conformer description state description
1 1 yes D*H 3Σg
2 1 yes D*H 1Σg

State 1 (3Σg)

Jump to S2C1
Energy calculated at CCD/6-31+G**
 hartrees
Energy at 0K-577.865576
Energy at 298.15K-577.864279
Nuclear repulsion energy47.895912
The energy at 298.15K was derived from the energy at 0K and an integrated heat capacity that used the calculated vibrational frequencies.
Vibrational Frequencies calculated at CCD/6-31+G**
Mode Number Symmetry Frequency
(cm-1)
Scaled Frequency
(cm-1)
IR Intensities
(km mol-1)
Raman Act
4/u)
Dep P Dep U
1 Σg 561 529        

Unscaled Zero Point Vibrational Energy (zpe) 280.6 cm-1
Scaled (by 0.9423) Zero Point Vibrational Energy (zpe) 264.4 cm-1
See section III.C.1 List or set vibrational scaling factors to change the scale factors used here.
See section III.C.2 Calculate a vibrational scaling factor for a given set of molecules to determine the least squares best scaling factor.
Rotational Constants (cm-1) from geometry optimized at CCD/6-31+G**
B
0.25699

See section I.F.4 to change rotational constant units
Geometric Data calculated at CCD/6-31+G**

Point Group is D∞h

Cartesians (Å)
Atom x (Å) y (Å) z (Å)
Si1 0.000 0.000 1.083
Si2 0.000 0.000 -1.083

Atom - Atom Distances (Å)
  Si1 Si2
Si12.1655
Si22.1655

picture of Silicon diatomic state 1 conformation 1
More geometry information
Electronic energy levels
Charges, Dipole, Quadrupole and Polarizability

State 2 (1Σg)

Jump to S1C1
Energy calculated at CCD/6-31+G**
 hartrees
Energy at 0K-577.834224
Energy at 298.15K-577.832951
Nuclear repulsion energy50.023286
The energy at 298.15K was derived from the energy at 0K and an integrated heat capacity that used the calculated vibrational frequencies.
Vibrational Frequencies calculated at CCD/6-31+G**
Mode Number Symmetry Frequency
(cm-1)
Scaled Frequency
(cm-1)
IR Intensities
(km mol-1)
Raman Act
4/u)
Dep P Dep U
1 Σg 598 564 0.00      

Unscaled Zero Point Vibrational Energy (zpe) 299.2 cm-1
Scaled (by 0.9423) Zero Point Vibrational Energy (zpe) 282.0 cm-1
See section III.C.1 List or set vibrational scaling factors to change the scale factors used here.
See section III.C.2 Calculate a vibrational scaling factor for a given set of molecules to determine the least squares best scaling factor.
Rotational Constants (cm-1) from geometry optimized at CCD/6-31+G**
B
0.28032

See section I.F.4 to change rotational constant units
Geometric Data calculated at CCD/6-31+G**

Point Group is D∞h

Cartesians (Å)
Atom x (Å) y (Å) z (Å)
Si1 0.000 0.000 1.037
Si2 0.000 0.000 -1.037

Atom - Atom Distances (Å)
  Si1 Si2
Si12.0734
Si22.0734

picture of Silicon diatomic state 2 conformation 1
More geometry information
Electronic energy levels
Charges, Dipole, Quadrupole and Polarizability