# Character table for the D10 point group

```D10     E       2 C10   2 C5    2 C10^3 2 C5^2  C2      5 C2'   5 C2"      <R> <p> <—d—> <——f——> <———g———> <————h————> <—————i—————>
A1      1.0000  1.0000  1.0000  1.0000  1.0000  1.0000  1.0000  1.0000     ... ... ....T ....... ........T ........... ............T
A2      1.0000  1.0000  1.0000  1.0000  1.0000  1.0000 -1.0000 -1.0000     ..T ..T ..... ......T ......... ..........T .............
B1      1.0000 -1.0000  1.0000 -1.0000  1.0000 -1.0000  1.0000 -1.0000     ... ... ..... ....... ......... T.......... ...T.........
B2      1.0000 -1.0000  1.0000 -1.0000  1.0000 -1.0000 -1.0000  1.0000     ... ... ..... ....... ......... .T......... ..T..........
E1      2.0000  1.6180  0.6180 -0.6180 -1.6180 -2.0000  0.0000  0.0000     TT. TT. ..TT. ....TT. ......TT. ........TT. ..........TT.
E2      2.0000  0.6180 -1.6180 -1.6180  0.6180  2.0000  0.0000  0.0000     ... ... TT... ..TT... ....TT... ......TT... ........TT...
E3      2.0000 -0.6180 -1.6180  1.6180  0.6180 -2.0000  0.0000  0.0000     ... ... ..... TT..... ..TT..... ....TT..... ......TT.....
E4      2.0000 -1.6180  0.6180  0.6180 -1.6180  2.0000  0.0000  0.0000     ... ... ..... ....... TT....... ..TT....... TT..TT.......

Irrational character values:  1.618033988750 = 2*cos(2*π/10) = 2*cos(π/5) = (√5+1)/2
0.618033988750 = 2*cos(4*π/10) = 2*cos(2*π/5) = (√5−1)/2

Symmetry of Rotations and Cartesian products

A1   d+g+i+k+2m               z2, z4, z6
A2   R+p+f+h+j+l+m            Rz, z, z3, z5
B1   h+i+j+k+l+m              x(x2−(5+2√5)y2)(x2−(5−2√5)y2), yz((5+2√5)x2−y2)((5−2√5)x2−y2)
B2   h+i+j+k+l+m              y((5+2√5)x2−y2)((5−2√5)x2−y2), xz(x2−(5+2√5)y2)(x2−(5−2√5)y2)
E1   R+p+d+f+g+h+i+j+k+2l+2m  {Rx, Ry}, {x, y}, {xz, yz}, {xz2, yz2}, {xz3, yz3}, {xz4, yz4}, {xz5, yz5}
E2   d+f+g+h+i+j+2k+2l+2m     {x2−y2, xy}, {z(x2−y2), xyz}, {z2(x2−y2), xyz2}, {z3(x2−y2), xyz3}, {z4(x2−y2), xyz4}
E3   f+g+h+i+2j+2k+2l+2m      {x(x2−3y2), y(3x2−y2)}, {xz(x2−3y2), yz(3x2−y2)}, {xz2(x2−3y2), yz2(3x2−y2)}, {xz3(x2−3y2), yz3(3x2−y2)}
E4   g+h+2i+2j+2k+2l+2m       {(x2−y2)2−4x2y2, xy(x2−y2)}, {z((x2−y2)2−4x2y2), xyz(x2−y2)}, {x2(x2−3y2)2−y2(3x2−y2)2, xy(x2−3y2)(3x2−y2)}, {z2((x2−y2)2−4x2y2), xyz2(x2−y2)}

Notes:

α  The order of the D10 point group is 20, and the order of the principal axis (C10) is 10. The group has 8 irreducible representations.

β  The D10 point group is isomorphic to D5d, D5h and C10v.

γ  The D10 point group is generated by two symmetry elements, C10 and a perpendicular C2′ (or, non-canonically, C2″).
Also, the group may be generated from a C2′ plus a C2″ (some pairs will yield smaller groups, though; choosing a minimum angle is safe).

δ  There are two different sets of twofold symmetry axes perpendicular to the principal axis (z axis in standard orientation).
By convention, the set denoted as C2′ has the x axis as a member, while the y axis is a member of the C2″ set.

ε  The lowest nonvanishing multipole moment in D10 is 4 (quadrupole moment).

ζ  This point group is non-Abelian (some symmetry operations are not commutative).
Therefore, the character table contains multi-membered classes and degenerate irreducible representations.

η  The point group is chiral, as it does not contain any mirroring operation.

θ  Some of the characters in the table are irrational because the order of the principal axis is neither 1,2,3,4 nor 6.
These irrational values can be expressed as cosine values, or as solutions of algebraic equations with a leading coefficient of 1.
All characters are algebraic integers of a degree much less than half the order of the principal axis.

ι  The point group corresponds to a constructible polygon, as the order of the principal axis is a product of any number
of different Fermat primes (3,5,17,257,65537) times an arbitrary power of two. Therefore, all characters have an
algebraic degree which is a power of two and can be expressed as radicals involving only square roots and integer numbers.

κ  The fact that the regular pentagon is constructible is known since antiquity; Eukleides already discovered a construction for it.
The double cosine of 2π/5 is equal to the reciprocal of the Golden Ratio of (1+√5)/2 = 1.61803.
Regular polygons of order 10,20,40,80 etc. are easily derived from the regular pentagon by successive halving of angles.
```

This Character Table for the D10 point group was created by Gernot Katzer.

For other groups and some explanations, see the Main Page.