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Questions tagged [correlation-functions]

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Green Kubo Relation

I am calculating viscosity of WCA fluid using the Green Kubo relation. I am also following the paper of Zhang et al. for the Time decomposition method https://doi.org/10.1021/acs.jctc.5b00351 where, ...
Lifelong Learner's user avatar
5 votes
0 answers
55 views

2D Infrared spectroscopy for bulk systems using molecular dynamics

There are some questions and answers (1,2) on this site regarding simple infrared and vibrational density of states calculations with molecular dynamics and there any simple algorithmic descriptions ...
mykd's user avatar
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4 votes
1 answer
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Effect of trajectory length and resolution on the Residence Time

I have tried to calculate Residence time using the residence time auto-correlation function defined as $$R(t) = \frac{\langle h(0)h(t)\rangle}{\langle h(0)h(0)\rangle}$$ In the calculation, I have ...
anupama's user avatar
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8 votes
0 answers
102 views

Which Exchange Correlational Functional should be chosen for calculation of optical properties in VASP using LOPTICS tag? [closed]

I am planning on calculating optical properties mainly dielectric constant using LOPTICS tag in VASP. Now for my electronic calculations I have been using HSE06 mainly because of higher accuracy of ...
Chan's user avatar
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8 votes
1 answer
1k views

VdW-D3 correction with HSE06 functional in VASP

I am trying to account for Vander waals correction in VASP. Now doing this for PBE is easy all one has to do is set IVDW=11 but the VASP webpage for DFT-D3 says ...
Chan's user avatar
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5 votes
1 answer
458 views

Programming auto-correlation function calculation

I have a set of data (heat flow) values in x, y and z directions for which I have to calculate the auto-correlation function to get the thermal conductivity. I have written a small Fortran90 code but ...
Pascal's user avatar
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7 votes
0 answers
187 views

Diffusion coefficient as a function of distance from the position autocorrelation function [closed]

I am trying to understand if my idea for the computation of diffusion coefficient as a function of distance is right or not. So, the diffusion coefficient as a function of distance is given by, $$D(z) ...
Roshan Shrestha's user avatar
9 votes
1 answer
991 views

What is autocorrelation time?

I'm writing this code of molecular dynamics about a pseudo-ideal gas in a box. The task is integrating the EOM for every atoms for a time-step dt fixed with the leapfrog method and measure the total ...
user4560's user avatar
8 votes
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87 views

How to use the HNC approximation to find the change in grand potential

I am reading Hansen and MacDonald's Theory of Simple Liquids, and I am going through Integral Equation theories. In section 4.3, they put forward the equation (4.3.14), $${\small \Omega _{\phi} = \...
megamence's user avatar
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7 votes
0 answers
432 views

What's the pair correlation function? What information does it contain? [closed]

This question is related to this VASP tutorial, in which the pair correlation function (or radial distribution function: RDF) is utilized to justify whether the solid silicon is melt by AIMD (ab-...
Jack's user avatar
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9 votes
1 answer
187 views

Derivation on correlation function and response functions in polymer physics

I am reading Introduction to Polymer Physics by Doi and I am having trouble understanding a derivation by him on the concentration fluctuations in polymer solutions. I have outlined his method and ...
megamence's user avatar
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7 votes
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120 views

Deriving relations for a hard sphere phase diagram [closed]

In Torquato's book "Random Heterogeneous Materials", he has written: $$\frac{p}{\rho kT} = 1+2^{d-1}\eta g_2 (D^{+})\tag{1}$$ where $g_2(D^+)$ is the contact value from the right-side of the ...
megamence's user avatar
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24 votes
1 answer
3k views

How exactly does one compute the vibrational density of states from the output of a molecular dynamics simulation?

There are many things that can be done with the output of a molecular dynamics simulation, but one of the more powerful things is the ability to compute the vibrational density of states (or the ...
jheindel's user avatar
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12 votes
0 answers
161 views

Correlation Functions in the Cluster Variation Method [closed]

I've been referring to Dr Mohri's paper [DOI: 10.1007/s11837-013-0738-5] for the cluster variation method (CVM). I wish to calculate the configurational entropy of a binary FCC system. Cluster ...
Hitanshu Sachania's user avatar