Questions tagged [software]
The software tag has no usage guidance.
579
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Correct way to transform RA-Declination to $x$-, $y$-, $z$-coordinates at the Galactic Center
I am simulating an object at the galactic center which has an initial position (RA and Declination) as 423 milliarcseconds and 525 milliarcseconds. The object is at a distance of 0.02pc from the Sgr A*...
1
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1
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44
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Does anyone have a good source for writing a Finite Volume Solver
As a pet project I want to try and write my own finite volume solver for a two-phase flow problem. However, while I understand the basics of FEM I have never written a code that solves anything before....
0
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0
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44
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Path integral Monte-Carlo simulations of the $t$-$J$ model
I'm working on the $t$-$J$ model, i.e, a strong correlation limit and effective low energy theory for the hubbard model. I am interested to simulate a two dimensional square lattice $t$-$J$ model ...
0
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0
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25
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Good resource to learn more about background reduction CERN data analysis
So I am working on a project which involves data analysis of LHCb data and I have to plot invariant mass histograms. Where can I learn more about background reduction in my analysis. I have to use ...
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0
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How to remove the baseline in the Raman spectrum without falsifying the spectral data. Measurement of anisotropy using SERS?
My goal is to study the anisotropy of the sample based on changes in the Raman spectrum as a function of angle. The sample was rotated around the Z-axis and changes in the spectra are visible in the ...
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0
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1
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98
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Sun-Earth-Moon-Spacecraft four-body simulation using MATLAB - unexpected results [closed]
I'm trying to simulate this four-body system by directly integrating the system of equations
$$\ddot{\textbf{x}} = \sum_{i=1\:i\neq k}^4 G\frac{m_i}{|\textbf{x}_i-\textbf{x}_k|^3}(\textbf{x}_i-\textbf{...
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1
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1
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84
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3D projectile motion simulator with drag is not constrained to a 2D plane
This is an example of the problem. I've set the initial velocities to be $(x,y,z) = (100,10,100)$ and the drag-coefficient and CS-area to be 1.
As you can see the motion is not constrained to one ...
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0
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24
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Simulation software for electrons scattering effects in materials
I am currently trying to find a software where I can simulate the effects of an electron beam hitting different materials of certain thicknesses, and get information such as how many backscatter, how ...
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0
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31
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Need Recommendations for Nuclear Reaction Modelling Software
Working on a project where I need to model nuclear reactions with different fuel pellet shapes. Does anyone have recommendations for software that's good for this? Any advice or experiences are also ...
0
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128
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Coupled quantum harmonic oscillator: Decomposition in terms of number basis representation for numerical implementation
Consider the Hamiltonian of a coupled quantum harmonic oscillator
\begin{align}
\hat{H}&=\frac{1}{2m}(p_1^2+p_2^2)+\frac{m\omega^2}{2}(q_1^2+q_2^2)+\alpha(q_2-q_1)^2
\\&=\frac{1}{2m}(p_1^2+...
- 272
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87
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Boundary/contour tracing of a binary image in Python
I'm studying percolation on a square lattice. I identify clusters on the binary lattice using the SciPy API ndimage.label. My goal is to study the external perimeter (hull) of each of these clusters. ...
0
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1
answer
57
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Lagrange multipliers method for a bead on a parabola-shaped wire [closed]
I have this simulation problem that looks very easy at first look (and maybe it is, especially using Lagrange equations of the 2nd. kind). I am using the Lagrange multipliers and I am kinda not sure ...
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-1
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1
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79
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Why would spherical velocity be zero along a numerically-integrated null geodesic?
I am writing a numerical solver for the null geodesics of an arbitrary spacetime metric, but currently mostly targetting black hole spacetimes. I am attempting to numerically integrate the geodesic ...
- 181
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96
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Construct an operator using outer product of two MPS using TeNPy
I am fairly new to Matrix Product State (MPS) formalism, but I've used Density Matrix Renormalisation Group (DMRG) techniques before. I'm learning to use TeNPy, and a particular problem I am trying to ...
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27
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Calculating cross terms for Haven coefficient using windowed MSD
My problem is that from this site: MSD Module I'm taking an equation that expresses the windowed mean squared displacement (MSD):
$$MSD(m) = \frac{1}{N}\sum_{i=1}^{N}\frac{1}{N-m}\sum_{k=0}^{N-m-1}(\...
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1
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0
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Toolkit to generate the most general gauge invariant Lagrangian for a given particle content
I am currently working on a BSM model for unification where I am adding scalars for unification. I add many scalars, so finding the most general gauge invariant lagrangian is becoming difficult. Is ...
-1
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1
answer
69
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Plotting ground Tracks with Python only using trigonometry [closed]
I'm trying to plot a ground track in Python from a TLE file without using explicit AstroPy or other packages. I've encountered a problem with the code that I can't figure out. The issue pertains to ...
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1
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75
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Cooper-Zare-Theory - Photoionization simulated in Python
My concrete problem is that I want to calculate cross-sections for photoionization transitions in argon in Python. For example from the excited state 3S^23p^56d into the continuum.
For this, I found ...
4
votes
1
answer
105
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Phase space density behavior in finite volume
I am trying to develop better intuition for the single-particle phase space density $f(x,v,t)$ and I am confused by the tendency of $f(x,v,t)$ to become wiggly in velocity space. Consider the simplest ...
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79
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Good text for writing a realtime physics solver?
What is a good, up-to-date, well-regarded text on writing physics solvers for (e.g.) game engines or realtime simulations?
In particular, treatment of numerical stability, convergence, asymptotic ...
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0
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46
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Is there any game for understanding elevator physics?
I'm a physics teacher and I'm wondering if there's any game for physics elevator problems (weight in accelerating elevator) that the student can play with to better understand in what situations the ...
1
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0
answers
92
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Komar energy using Mathematica [closed]
I want to check Komar conserved quantities for Kerr Newman metric using Mathematica. Is there any way to write a programming code for this?
Can anyone help me?
1
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1
answer
118
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(Weakly compressible) Smoothed Particle Hydrodynamics (SPH) and speed of sound
In SPH (weakly compressible approach) the Cole state equation is used to compute pressure from density:
$$p(\rho)=\frac{\rho_0c^2}{\gamma}\left(\left(\frac{\rho}{\rho_0}\right)^\gamma-1\right)+p_0$$
$...
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0
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43
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What machine learning technique can help generate spectrum line profiles?
I'm trying to work with Calcium-K line profiles from the Sun.
Image for reference. Please ignore the labels on the image and note that my profiles are not in image format (more info below).
I have ...
0
votes
1
answer
72
views
How to handle collisions in a game? [closed]
This must seem like a very basic question, but I'm building a game engine and need some help. Let's say that two objects, o1 and o2 collide with each other (defined by the first time their bounds ...
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1
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0
answers
63
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Good Mathematica package for computing Feynman graphs (resource request)?
I was wondering if anyone had any go-to Mathematica packages for computing higher-order Feynman graphs. Specifically ones that would allow me to construct higher spin fields like $h_{\mu\nu}$ and then ...
0
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0
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74
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Looking for the name of the spacetime interval with exponential
I have the following invariant: $$ds^2=e^{v(r,t)} c^2 dt^2 -r^2\left( d \theta^2 + sin^2(\theta) d \phi^2 \right) - e^{\lambda(r,t)}d r^2$$
for the centrally symmetric gravitational field. And I would ...
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1
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72
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How to find nonlinear conductance?
For quantum transport at the level of linear response, there is the Landauer-Buttiker formula. And for tight-binding models, there are programs targeting such calculations, such as the kwant package.
...
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3
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128
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How to use Python to get mathematical expressions in General Relativity [duplicate]
I'd like to get the metric tensor that describes a non-rotating, uncharged, perfectly spherical black hole whose radius grows with time (it gains mass). For now, I have:
$g_{\mu\nu}=\begin{pmatrix}
-c^...
3
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0
answers
106
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Is there a software that computes simple particle decay kinematics?
I was trying to figure out some details about a specific decay channel for a generic particle accelerator experiment. For instance if I have a proton proton collider with fixed energy, I would like to ...
2
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0
answers
105
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Variation of gravity in tetrad (vierbein) formalism using xAct or other computer algebra for wolfram language
I recently did some calculations in teleparallel gravity, where the fundamental variables are tetrad and flat spin connection. The Lagrangian density of teleparallel gravity is given by
\begin{...
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101
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Varying an action with respect to the metric in mathematica
I want to Varying an action with respect to the metric to obtain the Einstein equation $G_{\mu\nu}=k^2 T_{\mu\nu}$. Is there any way to do that in Mathematica? Can mathematica do that?
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57
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Sky coverage plot using Python/Astropy
I want to recreate a plot where the area that is not visible from a certain point on earth (latitude and longitude) trough a full year. An example of this plots for example can be:
Where in white is ...
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1
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Determining the location of light receivers using signals propagating in anisotropic media
Problem.
I have a set of $16$ light receivers with entirely unknown locations, and a pair of light transmitters with exactly known locations. One light transmitter is stationary, and located near to ...
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1
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76
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Modelling phase noise for self-hetrodyne method
I am trying to model the phase noise $\phi(t)$ of laser used in self-hetrodyne method using python code. The noise is time-dependent. The noise follows the condition that
$$<(\phi(t)-\phi(t-\tau))^...
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1
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58
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Optical software - thin film interference
I am currently using a software called "SCOUT" to thin film interference simulation, and I would like to know if there is a better software to do this type of simulations. My goal is to vary ...
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1
answer
108
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1-loop Feynman diagrams of $g \to gg$ in pure QCD
I'm very new to QFT, and I'm drawing one-loop Feynman diagrams of the process $g \to gg$ in pure QCD. I use MadGraph to generate all the diagrams by
...
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0
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68
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CalcHEP and FeynCalc giving different amplitudes--spin averaging?
I've done a simple amplitude calculation involving neutrinos and fermions scattering or annihilating through a BSM gauge boson. I'm checking with FeynCalc and CalcHEP, but the two are giving ...
user367500
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0
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45
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Five-point Function with five numerator terms
I need to calculate the 1-Loop integral
$$\int d^D q \frac{q_{\mu_1}q_{\mu_2}q_{\mu_3}q_{\mu_4}q_{\mu_5}}{((q-p_1)^2-m_1^2)((q-p_1)^2-m_2^2)^2((q-p_1)^2-m_2^2)(q^2-m_3^2)((q-p_2)^2-m_4^2)},$$
where $...
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0
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How to expand the existing basis set so that it becomes more complete?
This Mathematica.SE question https://mathematica.stackexchange.com/q/284679/ is physical too, so I have decided to duplicate it here.
I have a set of anisotropic gaussian basis set which describes the ...
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1
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160
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What's the best open source alternatives of COMSOL? [closed]
Good time of day. I need to solve system of differential non-linear equations for 3D system. It requires parallel computing on a cluster. Our lab lacks the license on Comsol. It is necessary to ...
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1
answer
124
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Calculating phase diagram of $\rm Al$-$\rm Cu$ with sublattice models
I want to calculate the phase diagram of $\rm Al$-$\rm Cu$ "by hand" in Python. The "regular" LIQ, FCC and BCC phases are all good (using the excess Gibbs energies from COST-507), ...
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0
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Numerical reference data for a 3D quantum system with Gaussian potential?
I'm currently writing a numerical code to solve the quantum system (in 3D) with an attractive ($v_0 < 0$) Gaussian potential,
$$ V(r) = v_0 \exp(-r^2/r_0^2). $$
It would be nice to have some ...
3
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0
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77
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2-particle irreducible (2PI) feynman diagrams
Let me preface this by saying that I'm not too code-savvy, which is probably why I need to ask this here. As a first step, I want to find a way to generate 2-particle irreducible (2PI) Feynman ...
2
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1
answer
104
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Smoothed particle hydrodynamics for solving diffusion equation
I'm a novice to the smoothed particle hydrodynamics method and I'm keen to know how it can be used to solve partial differential equations. In particular I want to know how to discretize the spatial ...
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51
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Numerators in LoopTools
I want to calculate the diagram
$$ \int \text{d}^D q \frac{q_\mu q_\nu q_\rho q_\eta}{(q^2-m_1^2)((q_1+p_1)^2-m_2^2)((q_1+p_1+p_2)^2-m_3^2)((q_1+p_1+p_2+p_3)^2-m_4^2)((q_1+p_1+p_2+p_3+p_4)^2-m_5^2)} $$...
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78
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1D Wave equations other than sinusoidal waves which can be graphed on Desmos Graph
I want to see waves equation other than the usual sine waves (or damped sine wave).
Im especially interested in graphing them on Desmos.
I have searched but everywhere either $sin(kx-wt)$ is shown or ...
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2
answers
220
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Visualizing 3D Lissajous curves
Lissajous figures are generally 2 dimensional, i.e. X and Y. But if an oscillation along a third axis Z (normal on the XY plane) is introduced, how would the resulting path look like? is there any ...
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0
answers
105
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Wick's contractions
According to Wick's theorem, we have
$${\left\langle {T\left[ {\hat A\hat B\hat C\hat D} \right]} \right\rangle _0} = {\left\langle {T\left[ {\hat A\hat B} \right]} \right\rangle _0}{\left\langle {T\...
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1
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94
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Difficulty solving conformal-bootstrap-like crossing equations using semidefinite-programming (SDP) via SDPB software
My question involves semidefinite programming (SDP) in the sense of attempting to find some vector $\alpha^{\mu}$ that satisfies the following conditions:
Normalisation: $\alpha^{\mu}n_{\mu} = 1$
...
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