6 votes

Exact Differentials and thermodynamics

First, requiring $dU$ to be exact leads to (1.4) because of Clairaut's Theorem - just to clear things up. Now, the requirement for $dU$ to be exact comes from the fact that it's a state variable. That ...
  • 592
4 votes

What constitutes a microstate?

A microstate is a state of an underlying mechanical theory. For classical physics it is classical mechanical state, a tuple of all particles positions and velocities. For quantum mechanics it is ...
  • 642
4 votes

What constitutes a microstate?

In classical mechanics fully describing a microstate requires knowing all the coordinates and momenta (we are talking here about generalized coordinates and momenta, not necessarily mechanical ones) - ...
  • 42.2k
3 votes

Exact Differentials and thermodynamics

The other answer gave you a mathematical perspective. This will provide a physical perspective. Physically, the difference between an exact differential and an inexact differential with respect to ...
  • 58.2k
2 votes

Confusion regarding density of states

Density of states with respect to energy is often defined as the number of states at a particular energy level This is not the right definition. The density of states $g$ is the function such that ...
  • 55.5k
2 votes

Understanding Maxwell relations by considering the differential changes of the enthalpy

The starting point is the fundamental differential $$dU = T dS - P dV\tag{1}$$ This is a fundamental result in thermodynamics and is obtained by combining the first and second law on a closed system ...
  • 1,348
1 vote
Accepted

What is the origin of the name "degeneracy" pressure and "degenerate" Fermi gas?

The term "degeneracy" comes from mathematics, where it refers to special "edge cases" in the math. The degenerate Fermi gas is an edge case (zero temperature) of a gas composed of ...
  • 6,153
1 vote
Accepted

Functional derivative of free energy

I assume you are referring to the section below Eq. (13). They did not calculate $\delta F=0$. It is the definition of equilibrium, that no infinitesimal field variation changes the free energy, ...
1 vote
Accepted

Does it help to find the ground state of a spin glass to maximize the number of ferromagnetic bonds?

As far as I can see, maximization of ferromagnetic bonds and minimization of energy are equivalent, so they require same computational time, which makes them in the same class of complexity, NP-...
  • 861

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