Questions tagged [algorithms]
For questions about algorithms and numerical methods.
19 questions
83
votes
6
answers
16k
views
Did the 2019 discovery of O(N log(N)) multiplication have a practical outcome?
Some time ago I've read this news article, Mathematicians Discover the Perfect Way to Multiply, reporting a discovery published in 2019, where Harvey and Hoeven[1] found a algorithm able to execute ...
- 4,148
45
votes
16
answers
3k
views
What are some recent developments in density functional theory?
In the book Materials Modelling Using Density Functional Theory: Properties and Predictions by Feliciano Giustino, a timeline of milestones in DFT was given for achievements between 1964 and 1996:
$$\...
- 9,237
26
votes
2
answers
3k
views
What are the "smart algorithms" applied to solve the "curse of dimensionality"?
The "curse of dimensionality" is an ubiquitous issue arising in both electronic structure and quantum molecular dynamics, which refers to the exponential scaling of computational cost with ...
- 3,983
14
votes
2
answers
184
views
Order of scaling for different algorithms
There are many different computational methods used in matter modelling. For example: solving multi-electron Schroedinger equation, DFT with different approximations, Quantum Monte Carlo, etc.
How ...
- 9,237
14
votes
1
answer
883
views
What is the speed/time required for DFT simulations?
I am currently designing a toy model to calculate an interatomic potential (for an infinite repeating lattice) this toy model needs to scale and perform better than DFT simulations. But sadly I have ...
- 141
9
votes
1
answer
924
views
How does charge mixing work?
When doing DFT calculations on certain magnetic materials, convergence can be difficult. This problem can be solved by changing the mixing parameters (e.g. AMIN and BMIX in the INCAR file of VASP). My ...
user5405
9
votes
1
answer
734
views
How to build cartesian representations of spherical Gaussian basis functions?
I'm trying to code an integral library for my own QC software from scratch. I need to use the spherical basis functions like in any other popular program. So, a D basis function is supposed to make ...
- 133
9
votes
2
answers
498
views
Evaluating the MSD of my simulation
I am running a molecular dynamics simulation of water in TIP3P, and I am storing the positions of my particles in a 2D array called relevant_positions. The number ...
- 4,181
9
votes
0
answers
139
views
Is there any literature that systematically analyzes current quantum chemistry algorithms using Big O notation for time and memory cost? [closed]
Big O notation is commonly seen in the papers on novel computational methods. However, only a few of them include rigorous analysis of the algorithm. Is there any literature that summarizes current ...
- 3,983
7
votes
1
answer
372
views
Have quantum computers been proven to speed up any matter modeling algorithm?
Personally, I think quantum chemistry is one of the most promising applications for quantum computers because the problem itself is fundamentally quantum, so there is an obvious argument why we should ...
- 6,804
7
votes
1
answer
355
views
What is the computational scaling of DFT energy vs gradient vs Hessian?
I am trying to understand the computational expense of calculating only the energy, versus the gradient/Hessian of the DFT energy with respect to nuclear coordinates. How do these scale with the size ...
- 7,171
7
votes
1
answer
961
views
When is coupled cluster preferred over DFT?
I know that coupled cluster is considered to provide better accuracy than DFT, but I am not sure for which materials science applications or types of molecules that this higher accuracy is considered ...
- 391
6
votes
1
answer
392
views
Define a geometry region using 'for' loop in MuMax3
I was trying to define regions using a 'for' loop.
Please find the regions:
...
- 193
5
votes
1
answer
51
views
How to Balance Translational and Angular Maximum displacements in a Monte Carlo Simulation of Non-Spherically Symmetric Molecules?
I'm writing a computer simulation code to model a system of non-spherically symmetric molecules, meaning that their state are described by both angular and translational components.
In typical Monte ...
5
votes
0
answers
63
views
How to calculate anisotropic exchange J $J_{xy}, J_{xz}, J_{yz}, J_{yx}, ...$ using 4-state mapping and DFT?
In this review, the authors present several schemes to calculate various quantities like single-ion anisotropy, DMI, and anisotropic exchange J using DFT. For instance, the DMI term in the y-direction ...
- 2,431
5
votes
0
answers
72
views
Parallel algorithms on unstructured closed graphs [closed]
Some of the work I do in the study of discrete dislocation dynamics (a branch of materials modeling) involves topological changes on a graph: changes in the connectivity of nodes, as well as deletion ...
4
votes
0
answers
32
views
How to estimate TFLOPS for calculation in Quantum Espresso?
My question is related to this. But I am more interested in knowing if there is a way to estimate computational requirements in terms of TFLOPS.
I was talking to someone who works in hardware design, ...
- 457
4
votes
0
answers
46
views
How can we identify the symmetry of the molecule from its IC table?
We are given the IC table for benzene in CHARMM format, which can be written as follows:
...
- 4,066
4
votes
0
answers
113
views
Rys Quadrature method for integrating over Gaussian basis functions: 1D integral recursion relation [closed]
I'm trying to implement the Rys Quadrature method for integrations of Gaussians, from scratch. I'm using this paper as a reference.
So, how does the overall recursion relation for evaluating 1D ...
- 133