Space group notation and related point groups

In summary, the conversation discusses space group #55, Pbam, and its properties including point group mmm and the presence of glide planes and mirrors. The conversation also raises questions about the relationship between Pbam and point group mmm, as well as the significance of the notation "D^9_2h mmm" in the table provided. Additionally, the conversation briefly mentions energy band structures in solids and the 10 irreducible representations of the point group for gamma in fcc structure.
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I'm looking at the space group #55, Pbam.

In the top of the file (see below) it has listed:

Pbam D^9_2h mmm Orthorhombic

Is this saying that Pbam is consistent with point group mmm?

It does not have three mirrors, it has two glide plane and one mirror.

If I look at the space group, I see that it can create a crystal that has C2h but not D2h.

Am I missing something? Is the "D^9_2h mmm" in the table telling me something other than the point group -- if so, what?

http://it.iucr.org/Ab/ch7o1v0001/sgtable7o1o055.pdf


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  • #2
What are energy band structures in solids?
 
  • #3
What are the 10 irreducible representations of the point group for gama in fcc structure?
 

What is space group notation?

Space group notation is a system of symbols and numbers used to describe the arrangement of atoms or molecules in a crystal structure. It includes information about the symmetry of the crystal and the positions of its atoms.

What is the purpose of space group notation?

The purpose of space group notation is to provide a standardized and concise way to communicate the structure of a crystal. This notation allows scientists to easily compare and analyze crystal structures and predict their physical and chemical properties.

How is space group notation related to point groups?

Space group notation is closely related to point groups, which describe the symmetry of individual molecules or atoms within a crystal. Space group notation extends this concept to describe the overall symmetry of the entire crystal structure, taking into account the arrangement of multiple molecules or atoms.

How many space groups are there?

There are a total of 230 unique space groups, which are classified into 14 different Bravais lattices. These lattices are based on the symmetry operations of translation, rotation, and reflection.

What is the difference between Schoenflies and Hermann-Mauguin notations for space groups?

Schoenflies and Hermann-Mauguin notations are two different systems for categorizing and describing space groups. Schoenflies notation uses letters and numbers to represent the different symmetry operations, while Hermann-Mauguin notation uses a combination of numbers and three-letter codes to describe the symmetry elements and their positions in the crystal structure.

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