Questions tagged [statistical-mechanics]

The study of large, complicated systems by means of statistics and probability theory, in order to extract average properties and to provide a connection between mechanics and thermodynamics.

3,528 questions
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What is the critical temperature for a BKT transition in the 2D quantum XY model with $S=1$ (not $S=1/2$)?

What is the critical temperature for a BKT transition in the 2D quantum XY model with $S=1$ (not $S=1/2$)? For instance, the classical XY model has KTc/J = 0.898 and the quantum XY model with S=1/2 ...
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Fluctuation-Dissipation Theorem [closed]

In statistical mechanics of equilibrium we say that the response is a linear function of the stimulus R(x)= cost* (1-x). How can I get it?
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Electrons residing in an orbit with energy lower than the ground state energy [duplicate]

Is it possible for an electron to reside in an energy level lower than that of the ground state? What happens to the electrons when an atom is brought down to 0K , do they come closer? What happens to ...
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Average magnetisation in the Ising Model

The Ising Model has energy given by $$E=-B \sum_{i} s_{i}-J \sum_{\langle i, j\rangle} s_{i} s_{j}$$ where $\langle i, j\rangle$ indicates that the second sum is over each pair of nearest ...
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Energy level below ground state

Can an electron occupy an energy level lower than its ground state? Do electrons come closer to each other at 0K temperature?
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Is it there any relation between an action and entropy?

I've found papers that seem to suggest that these concepts are the same, like this one: https://arxiv.org/abs/1005.3854 But I've found answers in Physics Stack Exchange that say that both are ...
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System of particles in classical mechanics and classical statistical mechanics

$\bullet$ Both classical mechanics and classical statistical mechanics can describe the properties of a system of classical particles. $\bullet$ In classical statistical mechanics, we assume that we ...
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Is evaporation a kind of phase transition?

When liquid is heat up to a critical temperature $T_{c}$, it starts boiling and converting to gas. In statistical mechanics, we learn that it is a phase transition. We studied all the properties near ...
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Question about notation of a Jimbo's paper

I am reading Jimbo's Introduction to Yang-Baxter Equations. And I am confused by the notation he used in the definition: Here he uses $u\in C$ without previously mentioning what is $C$. I guess ...
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Value of $\beta$ in Boltzmann statistics when degeneracy of quantum states is taken into account

The relationship between entropy $S$, the total number of particles $N$, the total energy $U(\beta)$, the partition function $Z(\beta)$ and a yet to be defined constant $\beta$ is: S(\beta)=k_BN \...
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Why doesn't the equipartition theorem force the rotational energy of a monoatomic molecule to be significant?

I'm reviewing the Feynman Lectures and in them he states that the rotational kinetic energy of a monoatomic molecule in a gas is insignificant due to a small moment of inertia. But wouldn't the ...