Can an Abelian Group Be Isomorphic to a Non-Abelian Group in Physics?

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SUMMARY

An abelian group cannot be isomorphic to a non-abelian group due to the fundamental property that non-abelian groups exhibit non-commutative operations, while abelian groups are defined by commutative operations. The discussion references the Molecular Symmetry group, which is generally non-abelian, and contrasts it with point groups, which are typically abelian. This highlights a common misconception regarding the isomorphism between these types of groups. The character table of irreducible representations can be constructed from the multiplication table of the group, as discussed in group theory literature.

PREREQUISITES
  • Understanding of group theory concepts, specifically abelian and non-abelian groups.
  • Familiarity with the properties of molecular symmetry groups and point groups.
  • Knowledge of character tables and irreducible representations in group theory.
  • Ability to interpret mathematical operations and their implications in group structures.
NEXT STEPS
  • Study the properties of abelian and non-abelian groups in detail.
  • Research the construction of character tables for various groups, focusing on symmetric groups.
  • Read "Group Theory and Physics" by Sternberg for insights into group representations.
  • Explore the implications of molecular symmetry in physical systems and its mathematical representation.
USEFUL FOR

Mathematicians, physicists, and students of group theory who are interested in the relationships between different types of groups and their applications in molecular symmetry and representation theory.

Konte
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Hi everybody,

I have a question: is an abelian group can be isomorphic to a non-abelian group?

Thank you everybody.
 
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In a non-abelian group, there are at least two elements A and B so that A*B=C but B*A=D with different D and C. this is not possible in an abelian group, so the two groups can also not be isomorphic.
 
DrDu said:
In a non-abelian group, there are at least two elements A and B so that A*B=C but B*A=D with different D and C. this is not possible in an abelian group, so the two groups can also not be isomorphic.

I thought so. But I asked this question because I have read this article of G.Bone and Co. http://dx.doi.org/10.1080/00268979100100021(in appendix page 71-72), which states that the Molecular symmetry group (MS) of a rigid molecule is isomorphic to its point group. Knowing that the MS group is composed of nuclear permutation-inversion operation, I verified by myself this group is in general non-abelian, and on the other side, point group are in general abelian. So, did they say something wrong?

Thank you.

Konte
 
Most point groups aren't abelian. Take a cubic group, like Oh as an example: Rotate first 90 deg, around x and then 90 deg. around y. Compare to first rotating 90 deg around y and then 90 deg around x.
 
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You are right, I missed it.
Thanks a lot.

I have another question, how to construct the character table of irreducible representation knowing the multiplication table of the group?
 
This can be arbitrarily nontrivial. Best have a look on a decent book on group theory. As you are mainly interested in the symmetric group, Sternberg, "Group theory and physics" might be what you are looking for.
 
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Ok. Thanks!
 

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