The Periodic Table

user116211

15:00

@Martin-マーチン: You read Mein Kampf?

CopperKettle

Tristan and Izolde

IͶΔ

Yohann (Johan)

Martin - マーチン

I guess I am, but I am also out of here now, for real.

IͶΔ

@Martin-マーチン Noooooooooo

@user36790 It's Kampf dammit

And of course, William

Martin - マーチン

@user36790 Of course not. It's utter garbage which was used to manipulate many people, even peoples.

CopperKettle

15:01

I started to read Mein Kampf, but it was too boring, so after a couple of dozen pages I dropped off.

user116211

@IͶΔ: what's going on?

user116211

@Martin-マーチン it is banned in Germany?

IͶΔ

@user36790 We're trying to guess @pH13's name.

user116211

@pH13: what's your name?

IͶΔ

@CopperKettle Pacifist! :P

pH13

15:02

@user36790 I think only until this year

CopperKettle

@IͶΔ It was not popular in Germany for a decade, until Hitler came to power.

Martin - マーチン

@user36790 No, the copyright was held by the bavarian government, but it expires this year.

pH13

the copyright is over now

CopperKettle

It's really not a gripping read.

Martin - マーチン

A commented version is I think being released.

user116211

15:03

@Martin-マーチン So will they publish?

pH13

there will be a commented version

user116211

Unabridged version so that neo-nazis can worship it?

Martin - マーチン

Utter garbage, a waste of paper and resources if you ask me.

pH13

@user36790 I like the "We're trying to guess @pH13's name." version ;D

@Martin-マーチン true story

Martin - マーチン

Ok... I'm afk.

user116211

15:04

@Martin-マーチン it is one of the best-sellers!

pH13

good night @Martin

IͶΔ

@Martin-マーチン Yeah right :P

pH13

@user36790 only because they gave it as gifts everywhere, etc ... for free, at weddings, etc

user116211

@pH13 No, not then; but now.

IͶΔ

Eats kiloampers per feet

user116211

15:06

@pH13 it ranked in top 10 in Amazon's Political and Propaganda booklist.

pH13

maybe in 'murica or whereever but not here

user116211

@pH13 BTW, what's your name?

pH13

@user36790 again - I like the guessing version of @IͶΔ

user116211

>,<

IͶΔ

@pH13 Which one?

I got you, Willard!

Willhelm

pH13

15:08

Wilhelm would be funny

user116211

@IͶΔ you got it.

IͶΔ

@pH13 Schrodinger

Schrodinger's son

Schrodinger's grandson

pH13

xD

maybe I should change my nick to that

IͶΔ

Schrodinger's orbitals

pH13

donitz? that's not a name here

user116211

15:10

@pH13 Schroedinger's Cat

IͶΔ

Ulrich

Steinberg :P

pH13

those are surnames :D

at least the second

Ulrich can be both

Ulrich Ulrich ... xD like Mohammed Mohammed

IͶΔ

Ulrich U. Ulrich

War Klauszecha

pH13

xD

user116211

@IͶΔ: Is it possible to calculate the inner product $\langle \psi_{sp^3}|\psi_{sp^2}\rangle$?

pH13

15:14

yeah, @IͶΔ ... is it?

user116211

@pH13: Is it 0?

IͶΔ

> How to make a German name in 3 easy steps:
> 1. Find a square-faced monster, a bulldozer with a name, or a scientist without glasses in a movie.
> 2. Add a Stein before the name.
> 3. Or add a Berg in the end.

3

user116211

Meant to say are they orthogonal?

user116211

@IͶΔ epic shit

IͶΔ

@pH13 I dunno. Is it?

pH13

15:16

funny that you are the one who get's this question

IͶΔ

@user36790 I never dared enough to try.

user116211

@IͶΔ >,<

IͶΔ

@pH13 I think we all agree that I'm very knowledgeable in Germannamology.

That's why.

pH13

well, indeed

@user36790 why would you want to do that?

IͶΔ

Stan Steinbeck

user116211

15:19

@pH13 hybrid orbitals are used as bases in molecular orbital; that's why I wanted to know if they are orthogonal

pH13

w00t?

user116211

@pH13 Am I wrong?

pH13

you will not see hybrid orbitals in MO calculations

IͶΔ

@user36790 ?

pH13

at a single atom, is it possible to have sp3 and sp2 hybrid orbitals at the same time?

user116211

15:21

3

Q: Hybrid orbitals forming molecular orbitals

My teacher showed me this diagram on how the hybrid orbitals of two atoms combine to form molecular orbitals. I was confused by this because I thought that VB and MO theories were two separate theories. In VB theory, atoms form hybrid orbitals that overlap, and the electrons are located in the ...

user116211

@pH13 got my answer

IͶΔ

@pH13 Dunno, do you call sp2.5 that?

pH13

@IͶΔ please flip a table for me

IͶΔ

15:33

@pH13 (/¯◡ ‿ ◡)/¯ ~ ┻━┻

pH13

thx

to end the speculations ... I'm philipp

IͶΔ

Philipp, Clausthal-Zellerfeld, Germany

9.7k 2 24 63

physical-chemistry organic-chemistry quantum-chemistry homework thermodynamics orbitals reaction-mechanism

Wait, really?

user116211

@pH13 double game

IͶΔ

Phillips are dominating Chem.

pH13

obviously not this one

not phillip ... that's the wrong way writing it

IͶΔ

15:37

I didn't want my spellcheck to nitpick.

@Phillipp this doesn't ping you. :'(

pH13

that makes me happy

IͶΔ

ಠ_ಠ

Hey Philipp

Phillipp

Phillipp hey

pH13

@IͶΔ Hey

IͶΔ

Phillipp

pH13

Muhamet

IͶΔ

15:45

Phillipp hey

pH13

Mochammett

IͶΔ

Phillipp

pH13

(/¯◡ ‿ ◡)/¯ ~ ┻━┻

IͶΔ

PHILLIPP

user116211

@pH13 Phillippp

IͶΔ

15:48

Phillipp is it "philipp" or "phillipp"?

Phillipp flip the flop

pH13

wilhelm was better

IͶΔ

Phillipp

Phillipp it's so fun to say "Phillipp".

pH13

thank you, it's a pleasure to make you happy

IͶΔ

Next step: Make a song for Phillipp

user116211

@IͶΔ: Is it necessary to have the basis set of MO to be orthogonal?

IͶΔ

16:02

@user36790 Hmm, how much do you want to study MO?

Just study the orbitals?

user116211

@IͶΔ -.-

IͶΔ

Is that a yes, or a no?

user116211

@IͶΔ means?

IͶΔ

Just tell me how much you want to study MO.

user116211

@IͶΔ I don't know; what comes before me, I try to get this. I'm reading Errol's Computational Chemistry.

IͶΔ

16:05

Haven't read that.

I think it'll all come to you after you read about them for a while.

user116211

amazon.in/gp/product/B001AP2YNK/…

pH13

MO's are orthogonal by constrain

user116211

@pH13 the basis

pH13

atomic orbitals are orthogonal by constrain, too

user116211

@pH13 when you use 2s and 2sp^3?

pH13

16:16

hybridisation is used primarily in school for educational purposes

user116211

@pH13 but ..

pH13

Please specify your question.

user116211

@pH13 butane.chem.uiuc.edu/pshapley/genchem2/a6/book.pdf

pH13

In this section you'll see how to use a simplified, localized bonding approach to molecular orbitals.

user116211

@pH13 It uses 1s orbital of H and sp^3 orbital of C as basis.

user116211

16:21

@pH13 So, is it wrong?

pH13

hybrid orbitals don't exist, they are only a mathematical construct to simplify bonding situations. there are many debates here on chem.se regarding this topic.

that depends on the question what you define as wrong

user116211

@pH13 But orthocresol also seems to accept it to use hybrid as basis ;/

user116211

5

A: Hybrid orbitals forming molecular orbitals

It is still LCAO-MO theory, but just dumbed down a lot. The difference is that, instead of feeding the "pure" atomic orbitals into the LCAO mechanism, you carry out an additional mathematical step in order to get orbitals that have nice directional properties, and you feed those into the LCAO mec...

pH13

every school accepts it

user116211

> Disclaimer: There are people who will debate exactly what "VB" and "MO" theories are. Wavefunctions exist in VB theory as well, except that they are constructed differently, and one might very well say that the simplistic MO theory above is, in fact, VB theory. Nevertheless, I am sticking to the introductory, qualitative notions of VB and MO theory here.

user116211

16:26

O.O

pH13

:)

user116211

@pH13 but ;/

user116211

10

A: How can the gauche-effect be explained?

The gauche effect is commonly explained with LCAO-based bond orbitals. LCAO is short for linear combination of atomic orbitals and implies that we can take two atomic orbitals $\phi_1, \phi_2$ and create two molecular orbitals $\psi_1, \psi_2$ from them by linear combination: $\psi_1 = a_1 \phi_1...

Wildcat

=^.^=

user116211

@Wildcat: Hi!

user116211

16:36

@Wildcat: Can we use hybrid orbitals as basis set for MO?

pH13

now schrödinger's cat is there to accept your qc questions

user116211

@pH13 hahahaha

pH13

@Wildcat did you manage the problems regarding your dissertation?

user116211

$$\textrm{Wildcat}\equiv\textrm{Schroedinger's Cat}$$

Wildcat

@pH13 so to speak

@user36790 not quite sure what do you mean by this...

pH13

16:39

@Wildcat should I ask for details? xD

user116211

@Wildcat Check Jan's answer

Wildcat

@pH13 the defence was postponed until September.

pH13

then you need to remember me in september to wish you good luck

Wildcat

well, you anyway use LC of AOs as MOs

so using LC of LC of AOs

user116211

@Wildcat $\psi = \psi_{1s} + \psi_{2sp^3}$ in $\ce{CH_4}$

Wildcat

16:41

won't give you any advantage

in principle you could

user116211

@Wildcat should the basis set always need to be orthogonal?

Wildcat

but by doing so you will reduce the variational freedom

user116211

@MadScientist: Plz speak ;)

pH13

@user36790 good luck

I will ping that

Wildcat

$\psi = \psi_{1s} + \psi_{2s} + 3 \psi_{2p}$

has more parameters

more LC coeeficients

@user36790 IIRC, not necessarily

orbitals has to be orthogonal, not the basis functions

but it is much easier to work with orthogonal basis

user116211

16:46

7

A: Do we need an orthonormal basis in Quantum Mechanics?

If two states are orthogonal, this means that $\langle \psi | \phi \rangle = 0$. Physically this means that if a system is in state $|\psi\rangle$ then there is no possibility that we will find the system in state $|\phi\rangle$ on measurement, and vis versa. In other words the 2 states in some s...

user116211

Related.

user116211

@Wildcat MOs need to be orthogonal but not the basis function?

Wildcat

in a sense, yes

user116211

@Wildcat Does it create problem as stated in the above answer?

Wildcat

What is the problem?

user116211

16:50

> If two states are orthogonal, this means that $\langle \psi | \phi \rangle = 0$. Physically this means that if a system is in state $|\psi\rangle$ then there is no possibility that we will find the system in state $|\phi\rangle$ on measurement, and vis versa. In other words the 2 states in some sense mutually exclusive. This is an important property for operators because it means that the results of a measurement are unambiguous.

user116211

@Wildcat If the basis sets are not orthogonal, then the result would be 'ambiguous'?

Wildcat

I don't see a connection there.

user116211

@Wildcat Why?

Wildcat

I mean the question from Physics.SE has almost nothing to do with LCAO-MO.

user116211

@MadScientist: What is your name? Reply and you will get 10 bucks.

user116211

16:53

@Wildcat Meant to say why? at one place, you want orthogonal basis set to get 'unambiguous' result but at other place it really doesn't matter?

Wildcat

This question from Physics.SE is totally unrelated.

user116211

@Wildcat so, in chem, we have no problem in using non-orthogonal basis set though the Mos must have to be orthogonal?

Wildcat

no problem at all

we usually use nonorthogonal basis

we have the overlap matrix then

user116211

@MadScientist: You have 5 min....

Wildcat

in our equations

user116211

16:56

@Wildcat In what context actually the answer in PSE is talking?

Wildcat

no

totally unrelated

user116211

@Wildcat O.O

user116211

@Wildcat So, both are true?

Wildcat

i think we discussed it myriads of times already

What is true?

user116211

@Wildcat ok let it go.

pH13

16:57

@Wildcat this will repeat year for year :D

user116211

@Wildcat: So, the conclusion is we can use hybrid orbitals as basis set; we can have non-orthogonal basis set but MOs must be orthogonal?

IͶΔ

@user36790 Whoa there.

Serenity.

Wildcat

When you express the state of a system as a linear combination of eigenstates of some Hermitian operator, there is no even question about do you need an orthonormal basis or not.

pH13

@user36790 I'm sure you want to delete that comment.

Wildcat

The set of eigenfunctions of a Hermitian (better say self-adjoint) operator IS orthonormal.

It is always is.

And that is logically consistent with QM.

BUT!

user116211

17:01

@Wildcat but?

Wildcat

The LC you have in LCAO-MO has nothing to do with expanding the wave function over set of eigenfunctions of some self-adjoint operator.

user116211

@MadScientist:

user116211

Wildcat

It is absolutely unrelated linear combination.

Well, it is related, of course. But not directly.

It is a different story.

user116211

@Wildcat This is the point I'm asking

Wildcat

17:04

But we've discussed that already.

1

A: How is a molecular orbital a 'quantum superposition' of the atomic orbitals?

Same story as with the previous question: quantum superposition is always expressed mathematically as a linear combination, but the converse is not necessarily true. Not each and every linear combination expression has something to do with real physical quantum superposition. In many cases it is ...

Not each and every linear combination expression has something to do with real physical quantum superposition. In many cases it is just a mathematical trick.

user116211

@Wildcat Yes, I remember that

Wildcat

Same story here.

Yes, you have LCAO.

But you do not interpret it as expansion over eigenstates of some self-adjoint operator.

That's just a convenient mathematical way of constructing MOs.

user116211

@Wildcat All superpositions are LCAO but not the vice versa

Wildcat

All superpositions are LC, but not all LC are superpositions.

user116211

@Wildcat got it.

user116211

17:11

@Wildcat: superposition is expansion over eigenstates of self-adjoint operator?

Aditya Dev

I got this from a post by a user. (I dont want to reveal the name): i.sstatic.net/92khU.jpg

IͶΔ

@AdityaDev Don't reveal the name. Give us the link so we can flag that comment.

Come on now, what's the hold up?

Aditya Dev

Someone already removed it :(

jonsca deleted it.

I censored the name.

IͶΔ

OK then happy ending.

Why did you bring it up?

Aditya Dev

I thought it wasnt deleted and I thought we could flag it.

user116211

17:20

@IͶΔ mins ago posted but deleted yesterday?

Aditya Dev

The first pic was taken yesterday. Then I forgot about it.

IͶΔ

@user36790 The former screenshot is older than the latter.

Aditya Dev

BTW, can I go ahead and give him a bounty? Or is there anything I am missing in my previous post about Z values?

IͶΔ

That's totally your choice.

Aditya Dev

$f(z,p)$ is cubic and it could have a maxima. But its not observed

pH13

17:36

@Wildcat you might want to laugh also ... I've got current SCF energies that are funny. It starts with -2.5kEh which is totally ok but then goes further to current -32MEh

Wildcat

:O

pH13

it's been -2.5kEh, -671kEh, -7.9MEh, -19.4MEh and now those -32MEh ^^

IͶΔ

19:58

Anybody in?

Wildcat

20:17

Into what? :D

Sᴋᴜʟʟ ᴘᴇᴛʀᴏʟ

Into the fire

IͶΔ

@Wildcat Go review the reopen thingy.

Wildcat

@IͶΔ 0 questions there.

IͶΔ

O_O

1

Q: How does a para-position strengthen the bonds in aramid fibers?

Aramid fibers are strong synthetic fibers. Kevlar is called a para-aramid, and it's outstandingly strong. Why does the para-position give Kevlar its strength? When the Kevlar monomers are in the para-position, will this make the chains closer (shorten the length of the bond), and make strong int...

organic-chemistry polymers

Wildcat

for some reason it is not in my reopen queue

anyway

done

IͶΔ

20:56

TY

ringo

22:54

@Greg could you please elaborate on what you mean by "many unstable systems?" Do you mean like supersaturated solutions? RE: chemistry.stackexchange.com/questions/46956/…

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