Unanswered Questions
1,264 questions with no upvoted or accepted answers
27
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How to calculate transition dipole moment from two known wavefunctions
I'm interested in calculating the transition dipole moment (TDM) from the information from two wavefunctions of different states. This is somewhat similar to calculating the molecular dipole moment ...
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What is d-orbital collapse?
When I was perusing the works of Schwarz on atomic structure, I came across the unfamiliar term of d-orbital collapse.
He describes it as a variation in energetic sequence from group 1 to 3 elements ...
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15
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Rotation around CC bond in 1,2-dioxetane: transition states and local minimum structures
TLDR:
What: Potential energy surface associated with rotation around CC bond in the ring-opened version of 1,2-dioxetane.
How: State average(4)-CASSCF(12,10)/VTZP constrained geometry optimizations ...
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12
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answers
309
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Accuracy of quantum chemistry calculations on iodine neglecting relativistic effects
Triiodothyronine is a molecule with three iodine atoms. If we attempted to calculate its properties with ab initio methods like Hartree-Fock or more complicated ab initio methods which included ...
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Understanding two-electron integrals in Gaussian 09
I was comparing the two-electron integrals (electron repulsion integrals, ERI) printed by various well-established packages (Gaussian, GAMESS, Molpro etc.) and observed that Gaussian is the oddball in ...
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11
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1
answer
303
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What is this golden looking substance?
I am currently messing around with gallium compromising aluminum. I am using a titalium lock which is just a brand of aluminum padlock and I put a gallium-indium euctic alloy on the surface of it. It’...
CommunityBot
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10
votes
0
answers
141
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Using symmetry and group theory arguments to explain iron(II) in a tetrahedral crystal field
I am trying to figure out how to explain $1s \rightarrow 3d$ spectroscopic transitions for $\ce{Fe^{2+}}$ in $T_\mathrm{d}$ symmetry. These transitions make up the pre-edge region in K edge X-ray ...
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10
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Why does the reaction of sodium nitrate, aluminium, and sodium hydroxide yield ammonia?
From Russian test problem 4301:
$$\ce{3NaNO3 + 8Al + 5NaOH + 18H2O -> 8Na[Al(OH)4] + 3NH3(g)}$$
How does ammonia evolve here? Is it that we get hydrogen gas evolving in the reaction between Al and ...
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10
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640
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Identifying alkyl ligands as π-donors or π-acceptors in transition metal complexes
Is there a systematic way to identify an alkyl ligand as a π-acceptor or π-donor in a transition metal complex?
Although various sources indicate that the weak field ligands are typically π-donors and ...
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9
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0
answers
194
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Why are vapours of xenon hexafluoride coloured?
According to Wikipedia,
[...] It is a colorless solid that readily sublimes into intensely yellow vapors.
It is clear from the above statement that $\ce{XeF6}$ is colourless in solid form. But why ...
CommunityBot
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9
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0
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Is there a reliable chemical theory that predicts pKa based on structure?
Obviously, there are general stability arguments that can be made to estimate relative pKas, such as evaluating the stability of the conjugate base of an acid, or thinking about how polarized the bond ...
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9
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430
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Vanishing integral rule for two-electron integrals
I understand the vanishing integral rule for a one-electron integral to be:
$$\langle i | \hat{O} | j \rangle = 0 \hspace{1cm} \mathrm{if} \hspace{0.2cm} \Gamma_O \neq \Gamma_i \otimes \Gamma_j$$
...
- 11.8k
9
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0
answers
514
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multielectron spin-orbit coupling and energy level
For multi-electron atoms for which the Hamiltonian (including the spin-orbit coupling) reads
$$H=\sum_i T_i-Z\sum_i V_i+\sum_i V_i^{\text{s.o.}}+\sum_{i>j}V_{ij}$$
The $T_i$ are the kinetic ...
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9
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1
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Order of Basicity of Nitrogen Trihalides
I was asked to arrange nitrogen tri-halides in order of increasing basicity. On looking up the answer online, it turned out to be the following: $\ce{NF3}$ < $\ce{NCl3}$ < $\ce{NBr3}$ < $\ce{...
CommunityBot
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8
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Why is octaoxygen diamagnetic?
I tried considering that according to LCAO-MO theory $\ce{O2}$ is paramagnetic, which is confirmed by experimental evidence. Since octaoxygen has the crystal structure in figure, I thought there is a ...
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8
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207
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Where is bifurcation situated on cyclohexane isomerisation PES?
I am wondering what does PES for cyclohexane isomerisation looks like.
I have two possibilities in mind but each has some kind of vagueness.
1) Starting from boat conformation minimum, followed by ...
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8
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347
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Isolating radium oxide
Why is radium oxide yet to be isolated when a wide range of other radium (II) compounds are known ?
- 6,801
7
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0
answers
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Type of British porcelain invented around 1917-1918
Being subscribed already for 30 years on Scientific American, I recently downloaded the whole archive, and I am now going through 1914-1918.
In the 26 January 1918 issue, on page 95, there is a small ...
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7
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101
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Why do nuclei move considerably slower than electrons
I've been trying to learn quantum chemistry at an introductionary level. While reading I've found out that the Born-Oppenheimer approximation seems to be the reason for the basic and crucial model of ...
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7
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593
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Does solvate isomers exist for coordination compounds with ammonia solvent as ligand?
I could find many sources confirming the hydrate isomerism(with water as solvent) but I couldn't find any information about any other solvent. In all the sources "hydrate/solvate isomerism" ...
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7
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Additional example determining Marcus parameters searched
Background / theory: The electron transfer in organic materials was formalized by the Marcus theory, introducing $|H_{ab}|$ to describe the how molecules (or more generally: sites) are coupled with ...
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7
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Why does lithium aluminium hydride appear grey?
Commercial lithium aluminium hydride is a grey compound, which loses a lot of reactivity the darker it is. Luckily you can clean it up to get the reactive white compound and the separated grey ...
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7
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Why isn't orthoboric acid soluble in cold water even though it has polar B-OH bonds?
This is the information I found regarding orthoboric acid's solubility:
Textbook (NCERT India): Sparingly soluble in water (didn't say what temperature - presumably cold) and highly soluble in hot ...
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7
votes
0
answers
109
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How well will molten iron chrysolite (fayalite) react with hydrogen?
The equation balances nicely, but would the reaction tend to proceed this way? What temperature and time would be needed?
$\ce{Fe2SiO4 + 2H2 -> 2H2O + 2Fe + SiO2}$
There is no problem with ...
- 6,801
7
votes
1
answer
448
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Is there a selective wet etch of Bi2O3 Bismuth Oxide?
I'm looking for a wet etch of Bismuth Oxide that does not etch $\ce{Bi}$ itself.
There are obviously chemicals that etch $\ce{Bi2O3}$, but $\ce{Bi}$ is pretty fragile, so almost everything I've found ...
CommunityBot
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7
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0
answers
4k
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Is there a difference between hydrated oxides and hydroxides?
My guess is that they are different.
I think hydrated oxides would have a lattice with the cation and oxide anions as lattice points and molecules of water trapped in interstitial spaces, while ...
7
votes
0
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379
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What is the most accepted explanation of aurophilicity?
Gold has a special property called aurophilicity. Inorganic chemistry by Huheey has some explanation, but that was not enough to clear the conception.
- 44.3k
7
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547
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Ligand strength - Coulombic effect and/or Electronegativities?
According to my teacher, these three Lewis bases generally decrease in strength in the following order:
Ammonia
Water
Hydroxide ion
I agree. However, he argues that their ability to act as Lewis ...
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7
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1
answer
3k
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Beer's law: UV-Vis absorbance values exceeding 2
In classical analytical chemistry, absorbance values in Beer's law can theoretically range from 0 to infinity.
As general rule of thumb neither high, nor very low absorbance are used for ...
- 29.2k
6
votes
0
answers
452
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How to explain oxidizing power from Molecular Orbital Theory
I am trying to explain the oxidizing property of $\ce{Fe^3+}$ in $\ce{H2O}$ and $\ce{CN^-}$ which is $\ce{[Fe(H2O)6]^3+}$ and $\ce{[Fe(CN)6]^3-}$.
The electrochemical reactions along with their ...
CommunityBot
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