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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Do neutron star merger studies probe beyond vacuum GR?

When mergers involving neutron stars and / or black holes are simulated (e.g. when predicting gravitational wave signatures for these mergers), obviously complicated numerical relativity calculations ...
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Generating Ising model steady state configurations

What is the most efficient way to simulate steady state configurations of the Ising model? I am just interested in having a large set of random steady state configurations of the 1D Ising model (with ...
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What are the Research Areas and Topics in Modern Physics for Bachelor's Students? [closed]

Research areas can be experimental, theoretical or computational using some software till now I know the basics of Matlab,Mathematica & Python.
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Restrictions on Initial Values for the first derivatives of a wavefunction, for a bound state in the time independent Schrödinger Equation?

The time independent wave function for a bound state given some potential function $V(r)$ is given by the time independent Schrödinger Equation $$E\Psi=-\frac{\hbar^2}{2m}\left(\frac{\partial^2\Psi}{\...
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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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Hadamard Gate implementation in MATLAB vs. IBM model [closed]

I am trying to build a circuit on IBM's quantum computer. I am checking every step as I go along on Matlab to make sure I fully understand everything. Everything was going well until I tried to add in ...
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2answers
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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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Hello guys. I have been trying to write an equation in Mathematica, can somebody help me [closed]

$\sqrt{\det[\gamma^{\mu \nu} F_{\mu \nu}]}$ Basiclly I need to expand this equation in some form like : $trF^4 + (trF^2)^2 + \sqrt{\det[F_{\mu \nu}]}$ where $\gamma^{\mu \nu}$ are Dirac matrices in $...
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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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How to Calculate Lyapunov exponent from time series data?

I have time series data which I got from correlation function. I want to calculate maximum Lyapunov exponents but I couldn't get it? Like this, I have computed correlation function (time series) data ...
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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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Running Rivet on Windows [closed]

I am trying to run Rivet on my Windows 10 Home Version through the Docker toolbox. I pulled the relevant image and was able to see all the listed analyses. By using the Bash command, I am able to get ...
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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? \begin{equation} \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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What would be the best potential functions for testing my numerical simulation of a wavefunction?

I created a numerical simulation of a wavefunction of a single particle in one dimension of space using excel. I tried putting the potential function $$\Large{V=\frac{\left(i\frac{\partial\Psi}{\...
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1answer
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How I simulate this in CST Studio? [closed]

I am trying to simulate this coaxial transmission line setup for EMI shielding. Placed the Aluminium sample as seen below (in the middle). I am new on this software, learned simulating the coaxial ...
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Problems with simulation of a spatial filter 4f setup (Python) [migrated]

I have a question about my code which computes numerically the output field of a 4f setup with a pinhole in the middle which works as a spatial filter. My setup consists of two lenses with 50mm focal ...
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3answers
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Are quantum computers able to simulate every physical process that a classical one can simulate?

I edited the question since this comment was (rightly) made: There are few things that are more annoying than questions where the question text is not self-contained. So: Quantum supremacy has been ...
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Contour Integration in Mathematica [migrated]

I need to solve an integral similar to following for a project: \begin{equation} F[p^2\_,q^2\_]\equiv\int_0^{\infty}dk\, e^{-k/\lambda}\, \frac{k}{k-b[p^2,q^2]- I\epsilon}\ln(k-b[p^2,q^2]) \end{...
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1answer
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Estimating the heat capacity of ising model

I am have written a Metropolis-Hastings algorithm and am currently trying to compare it to the analytical results for the 2D Ising model. The free energy seems reasonable but the heat capacity I'm ...
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Accelerometer readings simulation

I wrote software which generates a trajectory in an inertial frame. I'm trying to simulate an accelerometer reading, as if this accelerometer were moving along this trajectory. If this trajectory does ...
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1answer
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Is there software or code that is used to simulate hot ion plasma?

How are hot plasma simulated like fluid particles in CFD? Note: If this question is topic, i will eventually delete question but i only need an answer.
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1answer
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Numerically calculating Berry curvature in >2-band 2D systems?

The standard method for numerically calculating the Berry curvature of a 2D condensed matter system is given by Fukui-Hatsugai-Suzuki in this paper. They discretize $k$-space into a grid with tiny ...
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Deriving a model of a point-driven Chladni plate

Please note — this question considers a point-driven Chladni plate, not Chladni's classical experiment. I'm aware of various other questions concerning the latter here on Physics.SE. As the title ...
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Approximating the wave function of a bound state using a numerical method

Looking at the Schrödinger Equation $$i\hbar\frac{\partial\Psi}{\partial{t}}=\frac{-\hbar^2}{2m}\left(\frac{\partial^2\Psi}{\partial{x^2}}+\frac{\partial^2\Psi}{\partial{y^2}}+\frac{\partial^2\Psi}{\...
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2answers
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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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1answer
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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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$E\times B$ 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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13answers
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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 ...
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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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2answers
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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 ...
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Solving the Lane-Emden equation via Chebyshev differentiation matrices

Problem So I'm trying to learn spectral methods but I can't quite proceed for some reason. In particular, I have been trying to solve the Lane-Emden equation (which I know how to solve via ...
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1answer
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Discrete Harmonic Oscillator matrix representation of $x$ for Quantum Simulation

(The paper I'm referring to in this question is "Quantum simulations of one dimensional quantum systems") I've been trying to understand the paper above, specifically on constructing a ...
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1answer
86 views

Analytic solution to the Kepler problem from position + velocity initial conditions

I am writing a javascript program (web page) that uses iterative simulation to show the motion and mechanics of a satellite in orbit around the earth. So far, using only circular orbits, it has been ...
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2answers
114 views

Estimating partition function using Montecarlo methods

While working on a completely unrelated quantum computing problem, I ran into a quantity that can be mapped to a partition function of spins on a triangular lattice. It is not quite an Ising model, ...
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Which are the right configurations in the Markov chain of a Hamiltonian Monte Carlo algorithm?

I have a question about the Markov Chain Hamiltonian Monte Carlo (MCHMC). Hamiltonian Monte Carlo is known as Hybrid Monte Carlo too. I'll describe the steps of the algorithm. 1) We have at the ...
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1answer
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Computational Complexity of Crystallisation?

If we look at crystallisation as a tiling problem, i.e. filling the space with a given set of tiles of arbitrary shape. Then the time that it takes to solve this problem has to be bounded below by the ...
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1answer
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Matrix product state (MPS): Creating and understanding a specific 2-site Ising ground state?

I've been trying to better understand matrix product states (in order to implement them in code in the near future), so I'm considering small examples. I was wondering if I could get some ...
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1answer
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Double spherical pendulum simulation difficulties

I've been working on a simulation project of mine that I kind of need help with. So, as made obvious by the title, I am attempting to simulate the motion of a double spherical pendulum. I am writing ...
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0answers
51 views

Solving the Poisson-Schrodinger equations numerically

I need to find the solution to the Poisson- Schrodinger equation in the newtonian approximation, which are basically coupled differential equations given by: \begin{equation} \nabla^2 V=8\pi G M^{2}\...
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Position Based Dynamics - Cloth Balloon Constraint

I am attempting to implement the cloth balloon constraint from section 4.4 of this paper: https://matthias-research.github.io/pages/publications/posBasedDyn.pdf It is my understanding that after ...
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Degeneracy in linear tetrahedron method

In the linear tetrahedron method for the calculation of density of states, how does one circumnavigate the infinity error that would arise if two or more k-vertices of the tetrahedron have the same ...
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Operator constructions in DMRG?

I've been reading this paper to get a better understanding of DMRG: https://arxiv.org/pdf/1008.3477.pdf My questions come from equations 4, 5, and 9 on page 9 and 10. Eq (4) states that: $ \langle a_l ...
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How to find density of states (DOS) for a nanoribbon (NR)?

I have a nanoribbon (NR) which is constructed of $N$ 1D chains. The Hamiltonian is written as the following:(for only N=3) $$ H= \begin{bmatrix} H_0&H_{12}&0\\ H_{21}&H_0&H_{23}\\ 0&...

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