Re: My New Website

From: Lothar Brendel (l.no.spam.brendel_at_uni-duisburg.de)
Date: 06/04/04 

Date: Fri, 04 Jun 2004 13:41:31 +0200

Y.Porat wrote:
> Bjoern Feuerbacher <feuerbac@thphys.uni-heidelberg.de> wrote in message news:<c9ndqe$ode$1@news.urz.uni-heidelberg.de>...
>
>>Y.Porat wrote:

[...]

>>>more clear - i did to myself such 3d models
>>>and it helped me a lot though i am trained by my proffession
>>>to read 3d structures while i had to compute volumes
>>>*that belong to a single sphere* it was nearly indepensible
>>>or else you are fet lost in the littel 3d detailes
>>
>>Well, the 3D model shown in that document is far clearer than any
>>of the 3D pictures in your book. Apparently you have to practice
>>drawing them a bit more...
>
> -----------------
> what i show in my model is what Mr Brendel calles
> 'the primitive unit'

I don't know the picture of your model you're referring to, but somehow
I have doubts about that. Do you really show a rhombohedron there?

> and it is either i am apoor explainer
> or that both of you are slow about the problem.

What is your basis to get arrogant?

> actually it is confusing but we have to make it clear
> anyway:
> the problem with our discussion is that
> both of you
> *take it for granted* that the promitive unit is composed of
> *one atom*

No! I _don't_ claim that it is "composed of one atom" but that it
_contains_two_ atoms. And I can take it for granted because it is
defined so.

> while i claim that it is composed
> of more than one!

First you have to _define_ your "unit cell".

> and that is the core and crux of our discussion.
> i dont waht you to take it for granted i whant to prove
> or disprove *just that for granted assumption*
> it can be done only
> by findind how many atoms per say 1 cubic centimetr
> and !!!!!

Instead of (1cm)^3 let's choose (0.357nm)^3. We know from X-ray
scattering, that this voulme holds 8 atoms. Can't we conclude from that
1.75*10^23 atoms in one cm^3?

> listen care fully
> take the x ray obsrevations
> you see there (litrally see!) what is that we see there

Did you ever see pictures of X-ray scattering?

> we see some 'points' what ever it is or whaever you call it
> we can call it 'the primitive latice builder' ok?

No, that's _not_ what we see there. If you think otherwise, show us such
a picture.

What you call PLB is already known as "unit cell". There can be
different ones of different shapes and volume, but for a given crystal,
they have the same number of atoms/volume.

> so we have to finds out
> *how many primitive latice builders (PLB) we have
> in a cubic cm

Okay: The volume of diamond's conventional unit cell (one realisation of
what you call PLB) is known to be (0.367nm)^3=4.55*10^-23cm^3. Hence, in
1cm^3 we have 1/(4.55*10^-23)=2.2*10^22 of them.

> and divide the number of atoms with the number of PLD (per cm ^3)
> what i claim is that the answer will be a surprise.

If we use the density of diamond 3.51g/cm^3 and the mass of a carbon
atom 2*10^-23g, we get 1.76*10^23 atoms/cm^3. If we divide that by
2.2*10^22/cm^3 we get 8 atoms/unit cell, which we already knew. Where's
the surprise?

> it will be more than one atom in a PLB-
> not in all but in too many latice structures!
> (the diamond for sure for me more than one atom.)

So you dispute diamond to have a regular lattice altogether?

> and that will lead
> to some more revolusionary understanding about the
> structure of matter
> (so it desreves an effort)

How do you explain the agreement between
a) density + atom mass
b) X-ray experiments
c) STM experiments
?

> so we have to simply find the volume that one PLB ocupies
> if 'ocupies' makes it more clear than my 'avrage volume unit'

We know the volume of the conventional as well as of the primitive unit
cell (both are PLBs in your language).

> btw Mr Brendel you dont have to explain to me how nice and regular
> and exact and unambiguous- is the diamond structre i know it years ago
> anyway:
> TIA

TIA?

If you know that it is so nice and regular, how come that you claim it
has "more than one atom in a PLB- not in all but in too many latitce
structures"? So you claim that diamond is less regular than the so
called diamond lattice structure?

asks
        Lothar

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