Questions tagged [physics]
Questions related to the application of Mathematica to problems in physics.
795
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Simulating the Response of Charged Particles to Apertures with Inhomogeneous Electric Fields Passing through them
I have produced a simulation which allows me to observe a static electric field produced by a charged plate as it passes through some complex apertures in a different, oppositely charged metal plate.
...
- 23
5
votes
1
answer
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Error in Attempting Moving Boundary Fluid System
Recently I was attempting to solve a moving boundary fluid system on mathematica, which I have managed to convert into a coupled PDE-ODE system based on this helpful reference over here.
The equations ...
- 53
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50
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Implementing a 10-dimensional metric using diffgeo
I am trying to implement a 10-dimensional metric, namely a solution of type IIB supergravity equations of motion, using diffgeo by Matthew Headrick.
Physics
The metric is
$$ds_{10}^2=\sqrt{\frac{...
- 109
1
vote
1
answer
75
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How to create a matrix with multiple variables defining the elements?
I am a learner start using Mathematica to study quantum mechanics. In many cases, I am try to construct matrix with functions like this:
For example, let f be a function taking 4 variables x1,x2,x3,x4,...
- 19
8
votes
1
answer
350
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Droplet of water-alcohol mixture spreading due to evaporation-caused surface tension gradient
I am trying to solve a coupled system of PDEs for 2 functions h[t,r] and c[t,r], with initial conditions of ...
- 81
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100
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FEM: modelling 2D flow under periodic forcing
Despite many examples of periodic boundary conditions being presented, it remains difficult to obtain a periodic solution. Let us consider a simple example of a flow in a two-dimensional channel under ...
- 783
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0
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66
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FunctionInterpolation with some datapoints to start with [closed]
Motivation:
I am using FunctionInterpolation[COMSOL[x]] in combination with COMSOL to search for the interpolation of my COMSOL model.
COMSOL needs a lot of time to ...
- 11
3
votes
1
answer
117
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Error in Metropolis-Hastings with three states?
I wanted to create a simple example of the Metropolis-Hastings algorithm as a sanity check but the check failed and the results do not line up. I have a vector of energies $\vec E=(E_1,E_2,E_3)$ and ...
2
votes
1
answer
137
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Convergence plot of Lyapunov exponents
I am trying to reproduce the convergence plot of the four Lyapunov exponents for a string from this paper (page 12, figure 7).
The code that I have used till now to find the equations is given below:
<...
- 181
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2
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84
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1
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1
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Finding Hamiltonian from a perturbative Action
I am given a perturbative action $$\frac{S}{\mathcal{T}}=\int dt\sum _{n=0,1} (\dot{c_n}{}^2-c_n^2 \omega _n^2)+7.11 c_0^3+35.3 c_0 c_1^2+4.66 c_0 \dot{c_0}{}^2+1.32 c_0 \dot{c_1}{}^2-7.57 \dot{c_0} ...
- 181
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3
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318
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Neglecting higher order terms in a Lagrangian
I have a lagrangian which is modified by variable change. I want to neglect all the 4th order and higher terms in the new lagrangian. The code being used is given below:
...
- 181
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0
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56
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Variation with respect to inverse metric in a Lagrangian density
I am trying to vary the following Lagrangian density
with respect to the inverse metric appearing in the equation, but I am having trouble with how to write the right code in Mathematica.
I have ...
- 1
0
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1
answer
83
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create an animation of a string
I'm trying to create an animation of motion of a physical string, it should demonstrate a "jumping rope", but I don't know what function to use, I've tried parametric plot and vector plot. I ...
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2
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207
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Methods of Numerically Finding Function Minimizing Functional
Say we have some functional like the following: $H = (\partial_yf(y))^2 -w(y) f(y)^2 +f(y)^4/2$. This is the functional for the Gross Pitaevskii equation. Lets say $w(y)$, the trapping potential in ...
- 145
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51
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Error Integrate::ilim: Invalid integration variable or limit(s) in {0.1,0,1}. please help
I am making the code you can see below. I believe the error is that when I plug in values for x it also feeds back to the "dx" in the integration, how can I go around that?
...
5
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1
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257
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Poincaré Section from action
I am given a perturbative action $$\frac{S}{\mathcal{T}}=\int dt\sum _{n=0,1} (\dot{c_n}{}^2-c_n^2 \omega _n^2)+7.11 c_0^3+35.3 c_0 c_1^2+4.66 c_0 \dot{c_0}{}^2+1.32 c_0 \dot{c_1}{}^2-7.57 \dot{c_0} ...
- 181
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0
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42
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Gaussian 16 fchk and log file import in mathematica
I am working with Gaussian log files and fchk files imported into Mathematica and I noticed a few things.
The ExampleData in documentation for these files use Gaussian 03 output files, while the ...
- 535
14
votes
2
answers
225
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Stretching a mesh
Imagine I want to stretch a mesh with a 'rubberband-type' effect. That is, upon and elastic stretch from both side edges, the mesh centres simply scale as follows
where the points are seeds for ...
- 4,228
4
votes
1
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170
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Why do expressions with physical units not get simplified?
I am trying to calculate precise values for certain expressions, see the image below.
The output testZPF of the function $\Delta$Fn should be a single output. I am ...
- 129
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1
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80
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Mathematica: Partial derivative with respect to tensors
Anyone know how to do the partial derivative of a tensor in d dimensions on Mathematica ?
I want to implement something which will calculate directly like that :
1
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1
answer
87
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Set of three self-consistent coupled 'gap' equations
For a function of the kind of 5 variables, where this function must satisfy the following self-consistent coupled 'gap' equations.
I want to reproduce the graphics in the paper "Phases of QCD: ...
1
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0
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53
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How to plot dielectric susceptibility and scattering intensity for thin film superconductor?
I would like to plot the spatially varying (along the z-axis) dielectric susceptibility $\chi(z)$ of a thin film ($La_2CuO_4$) on top of a substrate ($SrTiO_3$) and the resultant scattering intensity ...
- 31
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68
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Gay-Berne potential in Mathematica
Cross-posting from Physics SE.
I am trying to make a plot of the Gay-Berne potential using Mathematica. I am following this paper and I am trying to recreate Fig. 2. This is figure 2:
To save time, ...
- 101
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2
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323
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How do I get the Schwarzschild solution from the Einstein Equations?
Consider the Schwartzchild-like metric $$ds^2=-A(r)dt^2+B(r)dr^2+r^2(d\theta^2+\sin^2\theta d\phi^2).$$ The Einstein field equations for this metric reduce to $$R_{\mu\nu}=0,$$ which is also known as ...
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2
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146
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Plot continuous field lines of bar magnet B field using StreamPlot
I want to plot the field lines of the B field of a bar magnet. The problem is that they have a very sharp bend when entering the magnet and Mathematica stops tracing the field lines.
Here is how I ...
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5
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1
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162
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How to impose Neumann boundary conditions describing quantum Hall effect?
I am trying to solve the following differential equation :
$$
\nabla\cdot\left(\begin{pmatrix}
c_1 & c_2 \\ -c_2 & c_1
\end{pmatrix}\nabla\phi\right) = 0
$$
on a rectangular domain [1,0]x[0,1] ...
- 345
1
vote
2
answers
47
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need dimension of solution space of system of non-linear complex equations
I've been trying to do this in Mathematica for several days but I'm getting almost nowhere. I need to know the dimension of the solution space of each of the two systems of nonlinear complex equations ...
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2
votes
1
answer
51
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What does the command '$FAVerbose = 0' do in FeynCalc
I have seen this right below the "<<FeynCalc`" command that loads FeynCalc.
$LoadAddOns={"FeynArts"}; <<FeynCalc;
...
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0
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42
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Refernce Solution Fails with NDSolve
I'm trying to crosscheck a solution of an ODE that is already implemented in Python. In Python I'm using a Newton iteration together with periodic boundary conditions to solve my ODE. In order to get ...
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0
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222
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Finding Coefficients in a Perturbation Problem related to Chaotic Dynamics
I am trying to reproduce the results from this paper: Chaotic dynamics of a suspended string
in a gravitational background with magnetic field
I am currently stuck with finding the coefficients.
First ...
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1
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4
votes
1
answer
156
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Plotting a field inside of a shape
I want to plot a field of vectors revolving on the inside of a torus in the positive x-direction. I don't know how to constrain the field on Mathematica. What would be the most efficient way to do ...
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2
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83
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A problem when solving an equation with symbolic variables
I asked a question a couple days ago and received a solution that worked for me at the time. But now I am seeing that the proposed solution fails for some other cases I need.
For example, if I just ...
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1
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218
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0
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42
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Extract quantum numbers from a string of second quantized operators within the SNEG library
I have been exploring the SNEG library. Suppose that after a series of computations I obtain the output:
$$ c_{i,j}^\dagger c_{x,y}^\dagger. $$
How can the quantum numbers $\{i,j\}$ and $\{x,y\}$ be ...
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0
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How to plot the lines of the magnetic fields of a Tokamak using StreamPlot3D?
I would like to plot the magnetic field lines of a tokamak.
Introduction
Since the magnetic field is solenoidal: $\nabla \cdot \vec{B} = 0$, it is possible to decompose it as:
$\vec{B} = \vec{B}_{T} +...
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1
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220
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Solving Lagrangian with Mathematica [closed]
I'm pretty new to Mathmatica but I'm trying to use it to find a Lagrangian and then find the equation of motion from the Lagrangian.
Think the method is correct but I just cant seem to get the syntax ...
- 17
2
votes
2
answers
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Can the CopulaDistributions be fitted?
This is an immediate follow-up to DoAny--which I did consider editing, clarifying and correcting in some respects.
But perhaps here I can put the immediate question at hand more directly (the emphasis ...
- 2,235
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1
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50
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List of eigenvalues of a list of abstract states
Suppose I have the states \Psi, \Phi and \Zeta and I also have the following relations given ...
- 207
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vote
3
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240
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Do any of the Mathematica CopulaDistributions (or others) fit well this sampled bivariate copula with uniform marginals over [0,1]?
I'm currently developing a data set that consists of two $50 \times 50$ matrices, which I designate as q1 and Q1. I strongly believe (bordering on formal proof [cf. Corollary 1 in marginalinvariance]) ...
- 2,235
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1
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72
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what is wrong with my code? it gives an empty graph [closed]
this is my code: and it gives me an empty graph?
...
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6
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1
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NDSolve solutions for modeling convection-coupled melting
I am trying to solve the convection-coupled melting benchmark in MMA 12.3 as presented in FEniCS/03-ConvectionCoupledMelting-MixedElement-AMR.ipynb. This model in MMA is based on the solution from ...
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2
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304
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Solving a Cauchy problem related to the pendulum
One end of a thread of length l = 1m is fixed, and a body of m = 1 kg is attached to the other end. The body is displaced counterclockwise by 30 degrees and then released. Plot the resulting Phi(t) ...
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1
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122
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Can this previously solved three-dimensional constrained integration also be solved with certain added products in the integrand?
In Solved3DConstrainedIntegration
the constrained three-dimensional (Hilbert-Schmidt-metric-based HSmetric) integration problem for the absolute separability probability of the two-qubit (quantum bit)...
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3
votes
3
answers
136
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Do loop so that I do not get double terms?
I have a Do loop where I generate quantum state equations <111||111>,<111||112>...<232||232>. This is 144 equations in total but I want both bra and kets to be seen as the same so ...
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1
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89
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NBodySimulation softening parameter
I'm simulating the orbit of a binary black hole immersed in some halo of particles and the simulation does not want to continue on for the specified amount of time. It always halts at a seemingly ...
- 463
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0
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121
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How do i solve two coupled nonlinear PDEs through Mathematica?
these are two relativistic fluid governing equations,
∂_t (γe)+∂_x(γev)=0
γ∂_t(γv)+∂_x[(γv)^2/2]=-(C/(1+C))*∂_x[log(e)]
where γ=1/sqrt(1-v^2) is Lorentz factor, <...
- 11
4
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2
answers
395
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NDSolve mathematica fluid mechanics
I have made Mathematica code for equation 16 from this paper. How can we make these streamlines I attached? I am using DensityPlot command but can't get it right ...
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2
votes
1
answer
73
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How to find the characteristic vibration frequencies of a system with any number of masses and springs using eigendecomposition?
I have created a program to solve any system of three springs and two masses using Mathematica's Eigendecomposition functions.
My goal is to solve a generalization of the spring system presented in ...
- 1,057