Questions tagged [computational-physics]
Computational physics is the study and implementation of numerical algorithms to solve problems in physics for which a quantitative theory already exists.
489 questions
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Numerical Simulation of Path Integral
I'm trying to code the path integral simulation described in this article. I followed all the instructions, but no matter how hard I try, my program won't work. Could someone please explain what I am ...
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Force oscillations during vc-relax of ZnCu₂SnS₄ with quantum espresso
I am running a vc-relax calculation in Quantum ESPRESSO for ZnCu₂SnS₄.
Cutoff energy: 75 Ry
k-point mesh: 6×6×6
SCF converges well (total SCF corrections ~1e-5 Ry)
Issue:
Total forces oscillate ...
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Are Velocity Verlet and Leapfrog Identical?
On the Wikipedia-page for for Verlet integration, under the Velocity Verlet heading it says
A related, and more commonly used algorithm is the velocity Verlet algorithm, similar to the leapfrog ...
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N-body simulation: are conservation of momentum and energy good parameters to determine accuracy?
I am writing an N-body simulation in C, using GSL with BLAS bindings and SDL2 for visualization. I decided to implement the leapfrog method, and so far I am quite happy with the result. I didn't ...
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Split-step Fourier method for ultrashort pulse propagation predicts everything, but not the spectral phase
I'm implementing in Python the split-step Fourier method (SSFM) to solve the non-linear envelope propagation equation (NEE), and I'm including second and third order dispersion (GDD, TOD), self-phase ...
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Poincaré section for double pendulum code improvement
I wanted to try numerical analysis of a chaotic system. So I decided to write my own code for the Poincaré section of a double pendulum in Python. The code works and the Poincaré section should be ...
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How to make sense of non planar Wilson loops on the lattice?
I am operating with a (more or less standard) Metropolis+Overrelaxation algorithm a series of Wilson loops on a $N_t\times N_s^2=48^2\times 16$ (2+1) dimensional Euclidean lattice. I am simulating ...
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Homogeneous isotropic turbulence in a box - field generation from energy spectrum
I am trying to reproduce a simulation of homogeneous, isotropic turbulence in a periodic box in order to analyze the decay of the energy spectrum and other parameters. To generate the initial field, I ...
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Problem while simulating spin polarized interacting SSH model
I want to simulate a spin polarized SSH model with Hamiltonian of the form
$$\hat{H} = v \sum_{i = 1}^N (\hat{C}_{i,A}^\dagger \hat{C}_{i,B} + h.c.) + w \sum_{i = 1}^N (\hat{C}_{i+1,A}^\dagger \hat{C}...
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Phi^4 theory simulation
i'm trying to simulate one dimensional phi^4 theory.
$$\frac{\partial^2φ}{\partial t^2}-\frac{\partial^2φ}{\partial x^2}+m^2φ+λφ^3=0$$
I'm using leapfrog method to integrate these equations of motion. ...
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Need advice for how to solve for potential flow on a sphere?
outsider to computational science here. This type of problem comes up in my field, however we focus on qualitative analysis, so I want advice for the computational side of things. This problem would ...
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Why is the concurrence $\theta$-independent while $ p(r, \theta) $ varies with $\theta$?
I am computing the concurrence for my system using the following formulas:
$$
g(r) = \frac{G(r)}{G(0)}, \quad f(r) = \frac{F(r)}{G(0)}
$$
$$
p = \frac{f^2 + g^2}{2 + f^2 - g^2}
$$
To compute the ...
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How can implicit Euler numerical method solve these ODEs?
In the implicit Euler method, we estimate the value of the function at a point using the slope at that point (x-value), which first seems absurd. As how can we know the slope at a point if we don't ...
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How to handle the Jacobian for the implementation of a symplectic numerical method
Define \begin{equation}H^{(\text{LR})}:= \frac{1}{\Delta x^{2}}\sum\limits_{n=1}^{N}\sum\limits_{m=1}^{N}\frac{u_{n}u_{n+m} + v_{n}v_{n+m}}{m^{1+\alpha}}\end{equation}
and $D = \text{diag}(d_1,\cdots, ...
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Gauß Laguerre-Code doesnt work
if wrote down a Gauß-Laguerre code, but for my function it doesnt work.
My function has the form f(x)=x^3/(e^x-^1).
Steps i have done: f(x) = x^3/(e^x-^1) * e^x * e^-x . Now i identify g(x)= x^3/(e^x-^...
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