# Questions tagged [boundary-conditions]

This tag is for questions regarding to the boundary conditions (b.c.) which expresses the behaviour of a function on the boundary (border) of its area of definition. The choice of the b.c. is fundamental for the resolution of the computational problem: a bad imposition of b.c. may lead to the divergence of the solution or to the convergence to a wrong solution.

1,165 questions
Filter by
Sorted by
Tagged with
210 views

25 views

### Cells in phase space in Maxwell-Boltzmann statistical analysis of thermodynamics

Can't the states overlap? For example, for one particle the value of spread of its $p_x$ is 1 unit from $p_x=0.5$ to $p_x=1.5$ whereas, for the other particle, is 1 unit from $p_x=1$ to $p_x=2$. Isn't ...
180 views

684 views

### In band gap theory, why can we use periodic boundary conditions?

In band gap theory, why can we use periodic boundary conditions when finding the wave function of free electrons in a conductor? Why do you think it is smoothly connected at both ends of the conductor?...
77 views

### Boundary conditions in quantum mechanics

I'm having some trouble understanding the role of boundary conditions in (non-relativistic) quantum mechanics. EDIT: The following text talks a bit about Bloch's theorem, but this was just supposed to ...
2k views

### Boundary conditions for crystals

As students on solid state physics, we are all taught to use the periodic boundary condition, taking 1D as an example: $\psi(x)=\psi(x+L)$ where $L$ is the length of the 1D crystal. My question is: ...
1 vote
35 views

### How does $\dot{q}_i p_i - H = \dot{Q}_i P_i - K + \frac{d}{dt}F$ will give the same EL and EoM for corresponding coords? [duplicate]

How does $\dot{q}_i p_i - H = \dot{Q}_i P_i - K + \frac{d}{dt}F$ give the same Euler-Lagrange equations and Equations of motion (EoM) for corresponding coordinates and allow us to determine a ...
249 views

### Temporal Gauge with periodic boundary conditions

In Yang-Mills theory with periodic boundary conditions in time, is the temporale gauge, i.e. $A_0 = 0$, well defined? Periodic boundary conditions would be $$A_\mu(T_2,x) = A_\mu(T_1,x).$$ Naively I ...
777 views

### Why is the total force at a free surface zero?

I am looking into waves on a free surface for which their are two main conditions: Kinematic condition: Particles on the surface remain on the surface. Dynamic condition: Forces acting on the surface ...
117 views

82 views

241 views

### Do even modes exist for e.g. pipes closed at one end?

This is really a question about terminology, The wavelength of a standing wave in a e.g. pipe closed at one end and open at the other is said to be $\frac{4L}{n}$, where $L$ is its length and $n$ is ...
47 views