# Tag Info

14

Yes, it is possible. Working with pure quantum mechanics means you will need to solve the many-body Schrödinger equation, which has no exact solution, so some approximation must be done numerically. Different approaches into solving this equations gave birth to different numerical methods, and some methods are more efficient for solving specific problems, ...

12

There are, of course, a lot of codes floating around. Which of them you should choose, depends on what you want to calculate exactly. Here I mention four possibilities: 1) CALHEP - this package takes you from a given Lagrangian through its Feynmann rules to the calculation of cross sections. 2) xloops - this package calculates the 1-PI Feynman diagrams ...

11

The problem seems to be that Mathematica here evaluates ${\rm Log}[\text{matrix}]$ by taking ${\rm Log}$ of each matrix element, which is not the correct mathematical definition of the complex natural logarithm of a matrix.

10

Goptical GNU-Optical Description Goptical is a C++ optical design and simulation library. Goptical is free software and is part of the GNU project. It provides model classes for optical components, surfaces and materials. It enables building optical systems by creating and placing various optical components in a 3d space and simulates light propagation ...

10

There are only two open source GR/tensor packages that I am aware of, Cadabra (coordinate-free) and Maxima/xwMaxima (coordinate based, ctensor, itensor and atensor packages)

10

Yes, this is possible -- I used to study it in undergrad, actually. I would say that the prerequisites are probably a few semesters of quantum mechanics -- enough to learn concepts like Born-Oppenheimer approximations, perturbation theory, and angular momentum theory. A course specifically in atomic and molecular physics would also help. As you say, and as ...

10

It simply looks like your initial condition causes the system to move through space. You need to work in the centre of mass frame. Set $$m_1v_1=-m_2v_2$$

9

I just discovered: opticalraytracer From the manual: OpticalRayTracer is a free (GPL) cross-platform application that analyzes systems of lenses and mirrors. It uses optical principles and a virtual optical bench to predict the behavior of many kinds of ordinary and exotic lens types as well as flat and curved mirrors. OpticalRayTracer ...

9

If you're trying to simulate a 2D solution of the Laplace equation (which is the only unambiguous reading of your post as currently stated; if that's not what you're doing then you should clarify your question with exactly what it is you're doing and how), then your code is wrong. The reason is that your results don't obey the maximum principle: a harmonic ...

8

For record: It looks like this topic really interests some people: http://markmail.org/message/nic7xrgf5uzed5c4 Newport was obviously thinking in the same direction: They offer an option to use SketchUp and provide 3D models of their mechanics and lenses—at least they used to, since this page does not exist anymore and the picture above was kindly sent to ...

8

This probably isn't exactly what you're looking for, but if you're looking for the time-independent bound states of a system, the Fourier grid Hamiltonian method may be applicable. Here is an application of it to the following strange-looking potential well: Here are a few low-energy bound states: And here are some of the high-energy states: I used a ...

8

Newton's shell theorem relies on Gauss's law, which in $d$ spatial dimensions implies a $r^{1-d}$ force law. Since $d=2$, the force should fall off as $1/r$. This explains why OP's first plot (with an $1/r^2$ code) fails to produce a vanishing interior force, while OP's second plot (with an $1/r$ code) produces a vanishing interior force. (Btw, the ...

7

For drawing Feynman diagrams with SVG, I have developed jQuery.Feyn to make it easier (see the screenshot below).

5

There is also optgeo, quite simple, but could be useful in your case, you can drag and drop lenses, mirrors, beamsplitters etc. It is free software: http://jeanmarie.biansan.free.fr/optgeo.html It is also in the ubuntu and debian repositorys.

5

There are the EMS, an add-in to Solidowrks, so you can simulate in 3D: (payed). Others: Amperes Quickfield MagNet Open source: MaxFEM

5

There is indeed a hybrid "quantum computer game" called Quantum moves (playable on Windows, Mac, Linux, Andriod, iOS) which is the first gamified citizen science project of Science at home. Quantum moves pursues two different objectives. On the one hand, it is an attempt to popularization of quantum physics, but it is at the same time a research programme ...

5

A thought experiment: after N steps, each of which create a change in angle $\Delta \theta$, we should end up with a normal distribution of angles with a standard deviation of $\frac{\sigma}{\sqrt{N}}$. When you change the step length, you therefore need to scale the standard deviation by the square root of that change, so that after moving the same distance ...

5

I don't believe anyone's released any compiled tools or libraries specifically for Bohmian simulations, but for a few simple examples in Python using RK4, Dane Odekirk has an excellent git repository here. I'd start with reading the pdf there, then look at the code—it shouldn't be too hard to follow. There are also several Mathematica examples here, and ...

5

I can't be certain that this is generating your peaks, but any tone that starts and stops won't be 100% pure; a pure tone has no beginning and no end. Consider a tone that starts at $0$ at $t=0$, vibrates for time $\tau$, and then turns off. As an equation, that looks like this: $$y(t) = \sin(2\pi f t)\, \Theta\left(\tau-t\right)\, \Theta(t),$$ where $\Theta(... 5 Your sampling rate is 48k at 55Hz, so each period is 872.73 samples. The size of your FFT is 65536. It fits 75.093 period of the signals. The algorithm takes 75 periods to plot the chart. This leaves 0.093 periods between consequitive FFT transforms. 0.093 periods at 55Hz correaponds to a frequency of 5.1Hz that matches the ghost frequency that you see ... 5 Your iterations are converging to a solution of Laplace's equation,$\nabla^2T(x,y)=0$, with your boundary conditions. This equation can be solved exactly in a rectangular area, with$T$being arbitrary specified functions along the borders. The solution technique produces an infinite series, as shown here: http://ramanujan.math.trinity.edu/rdaileda/teach/... 4 I thought a lot about this question since I graduated and began teaching. I think Adobe Illustrator is the best vector image software. It doesn't require any code to draw images; you only have to learn to use some "important" tools. I'm in no way a graphic designer or a professional in Illustrator and I drew this: Moreover,you can always find tutorials ... 4 I too use Mathematica for figures and found it wasn't a great leap from there to using it for drawings. You can draw 2D or 3D primitives pretty easily: Rectangle[{xmin, ymin}, {xmax, ymax}] and, like python/matplotlib, being able to parameterise everything allows you to redraw an image for multiple scenarios (or Animate or Manipulate it). For me the most ... 4 There is Qcraft, which is a mod of the game minecraft. According to its developers, It lets players experiment with quantum behaviors inside Minecraft’s world, with new blocks that exhibit quantum entanglement, superposition, and observer dependency. 4 There is OSLO - it's free (educational for a limited number of surfaces) But like all optical design software it's not like playing with LEGO blocks, you have to know a fair amount about optics to enter surfaces and interpret the results. I don't know of a drag-drop simple optics design package - the problem is that anyone who needs one generally needs the ... 4 As mentioned in the comments, you need one more piece of information to determine the magnitude of the velocity. You said that you might use the eccentricity, so in that case you can use the formula given here and deduce a quadratic equation on the velocity which yields: $$v= \sqrt{\frac{G M}{r \sin(\alpha)} (1 \pm \epsilon)},$$ where$G\$ is the ...

4

Sure thing. People do simulations in quantum chemistry all the time, as well as lattice QCD, although I don't know of any accessible ones. I used to enjoy watching these simple QM simulations when I was in high school. The problem with simulating a "quantum world" is a matter of computing requirements. Suppose you wanted to simulate just the spin of one ...

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