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Chemistry - MolPrincipalAxis

Syntax:
= MolPrincipalAxis(AtomsXYZ)

Description:
Returns the principal axis of inertia of a molecule.

The corresponding moments of inertia are given by the function MolPrincipalMoments. The i-th moment corresponds to the i-th column vector returned by the MolPrincipalAxis function.

AtomsXYZ: The cells that contain in column 1 the atomic symbol and in columns 2 to 4 the XYZ coordinates.

MolPrincipalAxis is an array function. Select 3x3 cells (3 rows, 3 columns) and enter the formula. Then press CTRL+SHIFT+ENTER to create the array formula.

Example:
Calculate the principal axis of CO2

     A     B     C     D
1   C     0     0     0
2   O     1    0     0
3   O     -1    0     0

Select cells B5:D7. Enter the following formula
=MolPrincipalAxis(A1:D3)
Press CTRL+SHIFT+ENTER

Result:
     A     B     C     D
1   C     0     0     0
2   O     1    0     0
3   O     -1    0     0
4
5          1    0     0
6          0    0     1       
7          0    1     0