# molecules's questions - Chinese 1answer

296 molecules questions.

### 1 Can we (in principle) obtain molecular bound systems by modelling fundamental particles and their interactions?

Is it possible, at least in principle, to start with the Schrodinger/Dirac/Klein-Gordon equations to model elementary particles and their interactions and to obtain in the end molecular bound systems? ...

### 1 Solving linear response in frequency domain

My question stems from a derivation given in chapter 12 of R. McWeeny's Methods of Molecular Quantum Mechanics for solving linear response equations via variational perturbation theory. (Linear ...

### Determining the sign (+/-) of the total work done on separating two molecules along a certain distance - AMBER16

I am currently moving two sugar molecules apart and would like to analyse the work done on separating them (and thus moving them apart from a distance of 3.5 Å to 30 Å). The values I am given by this ...

### 2 Existence of an electric/magnetic dipole of a molecule

I have a molecule with a symmetry group $S_3=D_3$. I have to determine if it has a non-zero electric and/or magnetic dipole moment using the representation theory. I'm using the book of Jones "Groups, ...

### What is the difference between a rigid diatomic molecule and non-rigid diatomic molecule?

1 answers, 965 views thermodynamics vibrations molecules
I started a mock paper for one of my entrance exams with this fairly easy question. I rearranged the equation and got 5/2, knowing that a diatomic molecule has a Cv of 5/2, i concluded that the answer ...

### 1 What does this notation mean: $\mathrm{O}_{2} \ \ a\,{}^{1} Δ_{g} ← X\,{}^{3}Σ^{-}_{g}$?

The notation (which I found in the abstract of this paper) is $$\mathrm{O}_{2} \ \ a\,{}^{1} Δ_{g} ← X\,{}^{3}Σ^{-}_{g}.$$ Any help with this? I understand it's talking about quantum states of ...

### 5 Wigner threshold law in photodetachment and photoionization

I am writing this question here because I have a problem in understanding the Wigner Threshold law in Photodetachment and Photoionization. The Wigner Threshold Law is given by: $\sigma$=$E^{L+1/2}$. ...

### 2 Under what conditions can molecules exist?

I am curious to know the conditions required for any two or more atoms to bond together and form a stable molecule. Is their a set of rules that should be satisfied?

### Simulating only small parts of macromolecules

0 answers, 7 views molecules molecular-dynamics
I've recently gotten into molecular dynamics (MD), and I was wondering the following: how can one simulate only small parts of proteins, e.g. up to 10AA? I am fond of e.g., Gromacs, where whole ...

### Surface tension molecular theory

1 answers, 13 views water surface-tension molecules
How does the surface of water behave like a stretched membrane? What's the cause for that? I know that the surface molecules experience a net force downward so there is dense layer of water molecules ...

### Does a Conical Intersection imply that the HOMO-LUMO gap in a molecule is very small?

0 answers, 13 views biophysics molecules quantum-chemistry
I came across some notes in which the author swiftly made this comment, that if there's always a large gap between the HOMO and the LUMO along a chemical reaction ("large" can mean at least bigger ...

### 11 Is Avogadro's law applicable for atoms or just for molecules?

I notice that online definitions of this experimental law always say, molecules or atoms. From the Wikipedia article on Avogadro's Law: $${\frac {V_{1}}{n_{1}}}={\frac {V_{2}}{n_{2}}}$$ The ...

### 15 Can a single molecule have a temperature?

A show on the weather channel said that as a water molecule ascends in the atmosphere it cools. Does it make sense to talk about the temperature of a single molecule?

### How can I know the volume occupied by one element in a compound?

I struggle to find how to estimate the volume occupied by one atom in a compound. As an example let's take $\beta$-Ga$_2$O$_3$, since that's the material on which I work the most. The crystal ...

### Where will pressure be stronger in these 2 pipe scenarios?

I initially started to be interested in fluid pressure and pipes to learn electricity. It seemed the only way I could help my head to get around some electrical concepts. That's the reason of my ...

### -2 Why do we measure boiling point of a liquid in an opened vessel [closed]

Can't we measure the boiling point of a liquid in a closed vessel

### Literature covering Hund's coupling case and anomalous Zeeman effect

I am taking a course in cold chemistry and different types of interaction seem to be an important cornerstone in the course. I am looking for a book that might cover the topics of molecules in ...

### 9 Can you make a metal denser by melting it and make it cool down under high pressure?

The answer is probably no. But can you make a metal denser by melting it and make it cool down under high pressure? Or would it just crack under internal stress when it returns to a solid? I'm going ...

### 10 Implications of parity violation for molecular biology

In biology, the concept of parity emerges in the context of chiral molecules, where two molecules exist with the same structure but opposite parity. Interestingly, one enantiomer often strongly ...

### Can I calculate the volume sputtering yield of a compound if I know the atomic component sputtering yields?

I'm running Monte Carlo simulations of a neon beam hitting a $\beta$-gallium oxide target. I set the initial bulk composition to be made of 40% gallium and 60% oxygen (Ga$_2$O$_3$). The simulations ...

### Is it possible to break a carbon dioxide molecule using electromagnetic waves?

I'm no expert in physics, but I was just wondering if breaking apart $\rm CO_2$ into oxygen and carbon would be possible using certain electromagnetic wave?

### 1 Bimolecular recombination in few words

I'm making a short seminar about VERY broad topic of fullerenes in photovoltaics, but I'd like it to be educational (not just full of words hard to audience to make them think I'm smart). In one of ...

### Pair correlation function vs Bond length distribution of a van der Waal dimer

For a weakly bonded molecular dimer (when two atoms are interacting through van der Waal (vdW) interaction). Do the distribution of pair correlation function and vibrationally average bond-length ...

### 3 Is the molecular term ${}^1\Sigma^-$ possible in a molecule?

The old question How to understand this symmetry in the wavefunctions of a diatomic molecule? explores how it is possible for a quantum state to have zero angular momentum about a given axis (giving ...

### 1 Why can we see the fundamental rotational-vibrational transitions of molecules like CO?

0 answers, 21 views wavefunction spectroscopy molecules
In rotational-vibrational spectroscopy, the "fundamental" transition is the one in the lowest electronic state between the first vibrational level ($\nu'=1$) and the ground level ($\nu''=0$). Since ...

### 1 Laser induced Ionization

We know that when a linearly polarised laser field interacts with a diatomic molecule ionization happens when the molecular axis is along the laser-field direction. However, in case of a circularly ...

### -1 Infer material characteristics from atoms/molecules configuration [closed]

2 answers, 26 views atomic-physics molecules
I'm not an expert in this field but I always wonder how deep is our knowledge about atoms and molecules from the point of view of the resulting material characteristics. The first example that comes ...

### If I'm using a compressor typically used for powering nail guns and other tools, why can't I make the air colder when I release it?

2 answers, 50 views energy pressure air molecules
I've always been fascinated in learning how to make liquid air, and I learned that there is a branch called physical chemistry, which deals in the manufacturing of different chemicals. My question is, ...

### 3 Is a mono-molecular spring possible?

3 answers, 67 views energy spring elasticity molecules
I have seen and read a lot of springs being used in the macroscopic world, and I also know that things can behave differently on a much smaller scale. My question is could a single piece of molecules ...

### How can I calculate the emission spectrum of a diatomic molecule from its spectroscopic data?

0 answers, 24 views spectroscopy molecules photon-emission
I want to model the emission spectrum of a diatomic molecule based on its tabulated spectroscopic data. I have seen papers where this has been done, but I have found no concrete formulas that give me ...

### Why water molecules move faster when heated?

2 answers, 180 views temperature velocity atoms molecules
In his first lecture about the nature of Matter and Atoms, Professor Feynman claims that the higher the temperature of the steam gets, the quicker the movement of Water molecules will be. I don't see ...

### How is the waveform deviation from the equilibrium related to the air molecule movement?

2 answers, 18 views acoustics molecules mean-free-path
I'm not sure if this is a stupid question. I've been considering the deviation from the equilibrium reflects the air pressure, with larger deviations reflecting higher air pressure. But in Reetz and ...

### 3 Does stirring water in a bucket in whirlpool keeps it warm?

3 answers, 9.385 views heat water molecules
I did an experiment when I was a teenager. I want to prove/see what really went on in that experiment. When taking a bath, take a warm water in bucket and start taking a bath. You will notice that ...

### 14 Is water really $H_2O$? On a comment concerning the quantum mechanical description of water made by Hilary Putnam [closed]

I wanted to pose a question here (also posted to r/physics a bit earlier) and was hoping the you all might be able to help. I was re-reading a book by the philosopher Hilary Putnam titled Naturalism, ...

### 2 Do solids have translational energy?

Along with having vibrational energy, do both crystalline and amorphous solids also have translational energy? I ask because I've always understood solids to have just vibrational motion/energy. But ...

### 14 Hot water freezing faster than cold water

This question has puzzled me for a long time. There is already a question like this on Physics.SE. John's answer to the question seems quite satisfying. But when I googled the cause I found this and ...

### 1 Degrees of freedom of a three dimensional polyatomic molecules

So the exact question is An ideal gas consists of three dimensional polyatomic molecules. The temperature is such that only one vibrational mode is excited. If $R$ denotes the gas constant, then ...

### How do molecules scatter light?

I've read that during Rayleigh Scattering, a photon passes through a molecule and the photon's electric field creates a dipole in the molecules. But what I don't understand is what happens next. How ...

### Fitting of force constants from vibrational frequency

From my understanding, the force constants in a molecule, for example methane, can be fitted using vibrational frequency data from experiment by diagonalising the hessian etc. My confusion lies in ...

### What are the p and n electrons?

In the study of spectroscopy (UV-visible, IR, FTIR etc.), I have found, "The ground state excitation of electrons (typically p and n electrons) takes place when a sample absorbs UV/Vis energy". What ...

### 5 What's the lifetime of the excited state when you shine light on molecules?

Let's say, when x-ray hits a molecule, an electron from an inner shell absorbs the energy and flies away, so there's a hole waiting for an electron to come down and fill it. How long does this hole ...

### 4 Mountains and their local effects on Earth's gravity

I was once a truck driver and can feel the inertia and kinetic energy on heavy loads while traveling. While climbing mountains in the Rockies I noticed gravity was different on the side of the ...

### Possible to predict the polarity of a magnet using only molecular analysis?

Is it possible to analyze the molecular arrangement of a magnet to predict which end is north? Or is it always a surprise until we see how it behaves near another magnet?

### 1 The “watering hole” frequency versus microwave oven frequency

1 answers, 132 views resonance molecules microwaves
I recently learned about the "watering hole," a group of frequencies between 1.42 and 1.66 GHz. I also read that microwave ovens operate at 2.4 GHz. If 21 to 18 cm (1.42 to 1.66 GHz) is the resonant ...

### -2 Amount of heat energy required to cause dissociation of $H_2$ molecules [closed]

The minimum amount of heat energy required to cause complete dissociation of $n$ moles of $H_2$ gas at constant temperature $T$ is? Do I have to do anything with binding energy out here in this ...

### Inter-molecular forces/energy vs distance diagram

0 answers, 57 views forces energy molecules
I am confused about the shape of the force vs distance and energy vs distance diagrams for molecules. I have always seen the following shapes: But recently, in my Fluid Mechanics course, the ...

### 1 Does gravity have anything to do with Van Der Waal's forces?

Does gravity have anything to do with Van Der Waal's forces? Just throwing this out there, I was wondering if they do because gravity is such a weak force and the VdW forces at a molecular level could ...

### 6 Why doesn't the H2 molecule have a permanent dipole while the neutral H has one?

According to the National Radio Astronomy Observatory, http://www.cv.nrao.edu/course/astr534/HILine.html, the 21cm line of hydrogen can be emitted by the neutral hydrogen atom due to the magnetic ...

### 2 Small inter nuclear separation limit for Diatomic molecule

2 answers, 81 views quantum-mechanics molecules
Let’s take the a simple $H_2^+$ molecule, where there is only electron which is $r_a$ away from the first proton and $r_b$ away from the other one. Let’s call the separation between the two protons \$...

### 5 What are sigma and pi bonds in physics language?

Chemists often discuss sigma and pi bonds. To a physicist, it's not easy to figure out what these actually are, as discussions tend to be full of lots of chemistry jargon about "antibonding", "...