Origin of correlated isolated flat bands in LK99

Re:Origin of correlated isolated flat bands in LK99 by dcow on Tuesday August 01, 2023 @01:10AM (#36952561)

As far as I understand, we're saying the same thing.

    isomer
    /'aɪsəmər/
    noun
    a compound that exists in forms having different arrangements of atoms but the same molecular weight

I'm using isomer to refer to possible different arrangements of "the LK99 compound". I see you're saying allotropes refers to diamond vs carbon (allotrope referring a single element vs isomer referring to compound).

That raises a question, what's the name for different crystalline structures of the same compound? Is that still an isomer or something different? I'm out of my element here.

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Re:Origin of correlated isolated flat bands in LK99 by jacquesm on Tuesday August 01, 2023 @01:14AM (#36952594)

An isomer can have different valences but still have the same overall chemical formula.

So just for an example (I have no idea how to put a tetrahedron in a comment :) ) a chain of C-C-C-C and C-C=C-C (which you likely can not synthesize) would be an isomer but C-C-C-C in one crystal lattice versus C-C-C-C in another crystal lattice would be allotropes.

The carbon in graphite sits in sheets (hence the possibility to form graphene), whereas the carbon in a diamond always forms three dimensional lattices.

edit nah: bad example, sorry, I can't find a good way to visualize this in text the 2nd C-C-C-C chain should have the last C dangling from the 2nd down.

edit2: examples are wrong, I should have used a more complex molecule for the isomer and the carbon can have either three or four other carbons hanging of it for the allotrope. tricky...

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Re:Origin of correlated isolated flat bands in LK99 by dcow on Tuesday August 01, 2023 @01:19AM (#36952624)

Just double checking, the definitions I'm finding for allotrope are specific to a single element.

    allotrope
    /'ælə,troʊp/
    noun
    a structurally different form of an element

I'm having trouble finding allotrope used to refer to different forms of a compound.

https://www.differencebetween.com/difference-between-allotro...

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Re:Origin of correlated isolated flat bands in LK99 by jacquesm on Tuesday August 01, 2023 @01:32AM (#36952698)

Yes, you're right, I should have used a more complex example for an isomer.

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Re:Origin of correlated isolated flat bands in LK99 by cyberax on Tuesday August 01, 2023 @01:25AM (#36952666)

Isomers are structurally different. Allotropes refer to variations of the same element.

You're looking at the word "polymorph": "(chemistry, geology) Any substance or mineral that forms different types of crystal."

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Re:Origin of correlated isolated flat bands in LK99 by dcow on Tuesday August 01, 2023 @01:28AM (#36952674)

Thank you.

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