Questions tagged [computational-physics]

Questions with this tag should be about computational physics, which is the study of physical situations with the use of software (commercial or in-house). Please note that details of writing and/or debugging code is OFF-TOPIC and should be asked at either Computational Science, Code Review or Stack Overflow.

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Modeling of Spatial Filtering of aberrated beam (~10mm) with Pinhole (~10μm) in 4f-Configuration -> size-constraints

I am trying to simulate a spatial filter in 4f-Configuration with an aberrated input beam to get a feeling for the remaining intensity and wavefront error depending on the pinhole size & ...
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For a Thermo-Calc database, is it possible to view the equation/parameters of the Gibbs free energy models?

I want to get the equations that model free energy for a given phase in a given alloy system (see attached image). I do not just want to get values of free energy for specific compositions. Is it ...
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Using air resistance (drag) in Python calculation

I am simulating a free fall with a function that needs to calculate the time it takes for a particular object to reach the surface, I got this program working without accounting for air resistance.. ...
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Numerical modeling of induced voltage

I have an arbitrary magnetic field that varies with time, and I'm trying to numerically model the induced current in a resistive loop over time. Details below. I'm building an electromagnetic ...
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What is the ideal software to simulate a falling maple seed (samara)?

I am completely new to the domain of CFD, so kindly pardon my ill-terminology ;p The task I have requires me to simulate the falling of a maple seed (or an equivalent CAD model) to record its vertical ...
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4-fermion interaction - vertices calculation with Feynrules

Dear Feynrules users and all physics enthusiasts, I was going to derive the 4-fermion vertices in Feynrules and to pass the generated model further to MadGraph and/or CalcHep. According to the most ...
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Using Runge-Kutta method with measurements of acceleration (what to do with half-steps?)

I'd like to perform a short-time motion estimation based on measurements from an Inertial Measurement Unit. If I use the Runge-Kutta method, I will need to compute the k values at half-time steps (Ref)...
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Verifiation the proof of mechanism represent by formula $pv^{(2-\gamma)}$=constant

I was evaluating equation $\frac{du}{dv}=-p$ and $u=\frac{1}{\gamma-1}pv$ which is internal energy of gas,by solving this equation, one will get $\frac{dp}{dv}=-\gamma \frac{p}{v}$,solving this DE ...
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Numerical integration of overdamped Langevin equation: explicit methods?

Assume we have a generic overdamped Langevin equation $$\frac{d {\bf{x}} }{dt} = {\bf{f}}({\bf{x}}) + B {\bf{w}}(t)$$ where $\bf{f}$ is a deterministic external (and fixed) force field (non ...
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Church–Turing–Deutsch principle

In what sense from the  Church–Turing–Deutsch follows that it is possible to simulate with one physical system all the other physical systems? I know that we can build logic circuits with a Toffoli ...
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How can I quantify the “temperature” of a system that is still evolving?

My system is a bunch of charged particles in a 1 dimensional harmonic potential. This is a computer simulation, and what I get is a list of the positions and velocities of each particle at every time ...
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Books and courses on Computational quantum mechanics

Can you please suggest the best book and course available on computational quantum mechanics using Mathematica and python or Matlab.
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Acceleration function of position and time

I have an acceleration function in python with position and time parameters and returns the acceleration value. I need the end velocity at a position ,start velocity is zero. how to calculate this ...
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Lattice Boltzmann method: properties of D2Q37 stencil and beyond

I am new in the world of Lattice Boltzmann method (LBM). I have just found in this paper [1] the following statement: A D2Q37 Lattice Boltzmann scheme correctly reproduces the equation of state of ...
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Initial Conditions for no-slip velocity (Walls)

For CFD initial condition, I want to know if i have to apply a very high velocity gradient on the wall of a pipe (internal flow) as it's the case when you study the freestream flow which surrounds an ...
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Monte Carlo sampling libraries for many-body Hamiltonians

This is possibly a very broad resource request question. I would like to know about the various Monte-Carlo libraries/codes that are used by researchers for sampling from the ground states or thermal ...
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Calculation of thermal expansion

how are the thermal expansion of a solid and the stress tensor related? \int_{\mathbb{R}^{3N}}\frac{\Delta E_p}{\Delta V}\rho_{H_h}(u)du=\frac{2}{3V}\int_{\mathbb{R}^{3N}}E_p\rho_{...
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Self-Consistent Ab Initio Lattice Dynamics

I would kindly like to know if anyone knows the QSCAILD method and if the schematic I wrote is correct. I referred to the following articles: https://arxiv.org/abs/2006.12867 and https://journals.aps....
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Explanation of track formation in scintillators(CsI:Tl)

So I was recently reading some papers on scintillation in inorganic materials like CsI: Tl. In all papers, cylindrical track formation has been mentioned. I understood that there is an incident gamma ...
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Algorithm for solving electromagnetic problems using only forces

Is there any fundamental issue to solving electromagnetic problems with the following algorithm? (practicality aside) i) Set position, velocity, mass and charge for a set of particles. ii) Compute the ...
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Algorithm to calculate diffusion coefficient

According to the Einstein relationship, the diffusion coefficient $D$ is $$\lim _{t\rightarrow \infty} \frac{\langle \left(\mathbf{r}(t)-\mathbf{r}(0) \right) ^2\rangle}{6t} = D$$ I have run a MD ...
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Is there such thing as well defined physics and math for atomic interactions? [closed]

We have a lot of good Newtonian physics simulation software out there (Bullet, PhysX, Havok, etc.), but I see none good for simulating atomic interactions (going deeper). I like to build one for ...
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$E\times B$ drift in strongly nonuniform fields

Potential is defined as $\{\phi,\, 0,\, A,\, 0 \}$; fields are static and depend only on the axial coordinate $x$: $E_x=-\partial_x\phi$, $B_z=\partial_x A$. Charged particle moves in the $\{x,y\}$-...
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Question about the VEGAS-algorithm for numerical integration

Disclaimer: I am not quite sure if this question belongs to Physics SE, if not feel free to move it. Question: I am currently using the VEGAS-algorithm (See e.g. here and here) and i am trying to ...
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Is there an equivalent of computation of physical processes in nature? [closed]

I was watching a waterfall in the Austrian Alps. There were thousands of water droplets falling down, splattering on the stones below. I thought - how does nature find out so quickly where each ...
139 views

Root Mean Square Displacement of Diffusion and Radial Diffusion Function

I read, that for normal diffusion the root mean square displacement $\sqrt{\langle x^2(t)\rangle}$ (for particles at the origin) can be interpreted as the mean distance the particles have with respect ...
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Canonical rotations that do not produce computational singularities

Intro On the topic of dynamical systems associated with 3-dimensional rotation of rigid bodies, you will always encounter singularities in the equations of motion that will produce computational ...