Unanswered Questions
671 questions with no upvoted or accepted answers
27
votes
0
answers
3k
views
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 ...
- 6,801
24
votes
0
answers
1k
views
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 ...
- 60k
15
votes
0
answers
358
views
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 ...
- 4,723
12
votes
0
answers
309
views
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 ...
- 742
11
votes
0
answers
1k
views
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 ...
- 9,881
10
votes
0
answers
88
views
Doubt in Zeeman effect for sodium spectrum
I am reading an atomic molecular physics book (for Indian universities). You may not familiar with it. But you can download it from the link if you wish.
So in the book it is mentioned that for normal ...
- 209
10
votes
0
answers
141
views
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 ...
- 101
10
votes
0
answers
2k
views
Why is the bond angle of N-N-N in hydrogen azide not 180 degrees?
Chen and Wang (2009) have reported an $\ce {N-N-N}$ bond angle in the hydrazoic acid molecule of $171.5$ degrees using B3LYP/6-311G** model. The wikipedia page for the molecule also reports a similar ...
- 10.7k
9
votes
0
answers
196
views
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 ...
- 38.4k
9
votes
0
answers
430
views
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
votes
0
answers
215
views
How to get defect-energy level diagram from PL data
I am reading this article Phys. Chem. Chem. Phys. , 2011, 13, 14902-14905 and seen that the authors have drawn a image of defect level using PL data
Can you explain me how this diagram can be drawn ...
- 2,758
9
votes
0
answers
514
views
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 ...
- 281
8
votes
0
answers
207
views
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 ...
- 534
8
votes
0
answers
2k
views
Tables/database/literature of specific or optical rotation
I'm looking for a comprehensive reference of experimental specific rotation or optical rotation data. It can be a published literature review, a free web database with API access or one that permits ...
- 43k
8
votes
1
answer
3k
views
Geometries of SCl2(OCH3)2 and SF2(OCH3)2
I am not able to understand the difference between structure of $\ce{SCl_{2}(OCH_{3})_{2}}$ and $\ce{SF_{2}(OCH_{3})_{2}}$.
I am already well versed with Molecular Orbital and VSEPR theories. I found ...
CommunityBot
- 1