Questions tagged [molecular-dynamics]

For questions related to the use of or theory behind classical or ab initio molecular dynamics.

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How to go from zero to hero in Machine Learning for materials modelling

I am interested in exploring the use of machine learning tools to accelerate molecular dynamics simulation probably by training machine learning potentials. While I have found some papers that apply ...
manuelpb's user avatar
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DIY molecular dynamics for Xenes on crystal surfaces; where can I get applicable open-source force field parameters that I can use in my scripts?

The linked question(s) below describes a DIY project to simulate how Xenes (honeycomb nets of atoms like graphehe) behave on single crystal surfaces. Behaviors include rotation, strain, and heigh ...
uhoh's user avatar
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Contribution in action from collisions for a gas?

So if I write the action for a gas: $$ S = \int (T -U) dt \tag{1}$$ where $T$ is the kinetic energy and $U$ is potential energy. I suspect there is a constant term (which does not affect the equations ...
More Anonymous's user avatar
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How to reproduce 2D small-angle X-ray scattering (SAXS) interferogram of water via ab-initio MD methods?

I am trying to reproduce the 2D SAXS interference pattern of bulk water via ab initio MD methods as shown in the figure below: The main aim is to recreate figure (a) via averaging MD configurations ...
mykd's user avatar
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How to analyse structure factors calculated from a mixture of isotropic amorphous substrates

I am looking for a way to computationally analyse the interactions between two molecular species (as solute and solvent) in an isotropic mixture using X-ray scattering. Is there a guideline as to how ...
mykd's user avatar
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How to calculate small and wide-angle X-ray scattering spectra for the hydration shell restricted by a distance radius criteria

My main aim is to extract the SWAXS spectra for the hydration shell surrounding a solvated molecule and I am unfamiliar with the idea of excluded solvent volume. I tried looking online but many ...
mykd's user avatar
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Apparent conservation of potential energy in NPT simulation?

I was examining a system with a problematic equilibration (more details given at the end, but probably unnecessary to answer the question), and came upon what is presumably a pretty basic conceptual ...
Barbaud Julien's user avatar
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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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Loading Gromacs Trajectories using ASE (Atomic-Silumation-Environment)

I am trying to study some trajectories generated using Gromacs. I have been given tpr and pdb files of the simulation. What might be the most effective way to load them in ASE? Or is there way to ...
Saha_1994's user avatar
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Regarding use of GCMC to add water molecules

I am working on a goethite system, and wish to fill the unit cell with water molecules for AIMD simulation using quantum espresso. For this, some papers[1],[2] indicated the use of Grand Canonical ...
ansonthms's user avatar
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How to extract Lindemann Index from LAMMPS dump files?

I used a python code to extract Lindemann index from dump files. But the problem is the code works fine with dump files with little amount of data and atoms. When I use large files if shows overflow ...
Lammps_beginner's user avatar
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ASE/XTB: zero temperature and stress in MD simulation

I want to see how the volume and pressure of my cell is changing during a MD relaxation in ASE. I used the atom.get_volume() and ...
Marco Di Gennaro's user avatar
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OOM Error Calculating ESP Charges with Psi4

I'm trying to create a script to generate partial charges for a given .dat file. As an example of my process, I'm currently using gromacs to run minimization on a box of propane. It outputs a min.gro ...
asquith's user avatar
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MMGBSA: Electrostatic and van der Waals

I ran a molecular dynamics simulation using Gromacs 2023.2, with the CHARMM36 forcefield. And I ran a per-residue energy decomposition calculation using gmx_MMPBSA, with MMGBSA model. MMGBSA model ...
Bruce Zhou's user avatar
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Quantifying binding free energy?

I have binding free energy of some organic molecules on a surface, computed through Umbrella sampling. For now, I only have experimental data on the binding energy of some of these molecules. Is it ...
Roshan Shrestha's user avatar
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How to create a water droplet (half-sphere) on a rock (quartz) surface

I am to Equilibrate a uniformly distributed spc water molecules at 300k in 50x50x50 box. Water density is taken to be 1000kg/m3. Simulate the system in the NVT ensemble. The spc water is modeled using ...
Abdul Rauf Kaunda's user avatar
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Density of a spherical droplet of water on top of graphene

I produced a spherical droplet of water by having a box of water (sufficient water molecules inside the box to give the right density of water) on top of a 2d sheet-like graphene. The box becomes a ...
Roshan Shrestha's user avatar
3 votes
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DFPT vs analytical nuclear gradient

I have read some literatures about the gradient wrt. atom positions of the DFT energy, and find different methods one commonly used in MD(analytical nuclear gradient,pulay's paper), and another ...
Fadelis Hu's user avatar
3 votes
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How to perform atomistic spin dynamics (ASD) Ab Initio Molecular Dynamics (AIMD) using VASP?

I have tried normal AIMD simulation using VASP for Non magnetic materials. Now, I am interested to perform the molecular dynamics simulations for the finite temperature for Magnetic materials to ...
prakash g's user avatar
3 votes
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How to get energy gap change at specific high symmetry points during ab initio molecular simulations?

I want to check the energy gap change during finite temperature ab initio molecular simulations. The results may look like this picture: How can set aimd simulation to get this result in VASP?
Tieyuan Bian's user avatar
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Read and run lammps water model in ASE

I want to read a lammps data file in ASE, for instance the TIP3P or the SPC model. The lammps examples provide the input script and the data file, which work perfectly. ASE is not able to read the <...
Marco Di Gennaro's user avatar
3 votes
0 answers
37 views

Running molecular docking simulation between two proteins

i did run docking simulation between two proteins on HADDOCK server but now i want to run a simulation of complex (protein+ligand and protein) is it possible with HADDOCK and how can i use it best ...
Imane Yamari's user avatar
3 votes
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101 views

How to check the units from ASE get_forces() function?

Here is a little python code that loops through a molecular dynamics trajectory (performed with the ASE package) and outputs the forces on the atoms at each frame: ...
breadcrumbs's user avatar
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Is it possible to find a cubic supercell for a non-cubic crystal structure?

Suppose that we have a crystal material with a non-cubic unit cell. E.g. $\alpha \neq \beta \neq \gamma \neq 90^{\circ}$. Is it possible to find a supercell such that $\alpha = \beta = \gamma = 90^{\...
ado sar's user avatar
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Are the Lagrange multipliers used in Kohn-Sham DFT/HF-based quantum molecular dynamics real valued?

I have seen it written in several places that the matrix of Lagrange multipliers used to impose orthonormality in quantum molecular dynamics schemes based on Kohn-Sham DFT or Hartree-Fock for instance,...
aQuarkyName's user avatar
3 votes
1 answer
111 views

Include Li+ in force field for Molecular Dynamics

I want to perform some MD including Li+ ions. Specifically I am interested in Li-TFSI (aka Lithium bis(trifluoromethanesulfonyl)imide). I tested both the ATB repository and LigParGen and neither can ...
Marco Di Gennaro's user avatar
2 votes
0 answers
55 views

Method for Energy Computation of Protein Structures

So far i have found only one paper that describes how we can compute protein energy while doing MD simulation: Nishikawa, Ken, Motohisa Oobatake, and Tatsuo Ooi. "Method for Energy Computation ...
user366312's user avatar
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2 votes
0 answers
79 views

Help with LAMMPS create_atoms and delete_atoms command

I am running polymer simulations inside a spherical region. I have loaded the polymer using read_data command. I want to add fixed number of individual new atom types inside this sphere while it ...
Roni Saiba's user avatar
2 votes
0 answers
45 views

Where should we compute `Trajectory` in this listing?

Cross-posted here. I have the following listing for a barebone MD simulation: ...
user366312's user avatar
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2 votes
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How to estimate the minimal distance between atoms for which a pseudopotential-based AIMD gets forces correctly?

I am doing ab initio molecular dynamics in VASP. As far as I know, pseudopotentials approximate all-electron potential far from the nucleus, and deviate from it near the nucleus. When some of my atoms ...
Vladislav Gladkikh's user avatar
2 votes
0 answers
28 views

Interaction energy of two cartesian quadrupoles?

I am looking for a complete description of the interaction of two traceless cartesian quadrupoles. Even just an implementation online would be quite useful. The problem I am having is many of the ...
jheindel's user avatar
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2 votes
0 answers
59 views

Simulate liquid solvent mobility through a gel polymer electrolyte

I would like to simulate a liquid solvent (such as TEGDME) embedded into a polymeric cage (such as PEGDM). What is the most meaningful approach to estimate transport properties in such a system? Three ...
Marco Di Gennaro's user avatar
2 votes
0 answers
35 views

How to bond two laminates (same material) separated by distance using compressive pressure in LAMMPS?

I would like to simulate the bonding process using compressive pressure for two layers of the same material. Applying a uniaxial strain and using the deform tag in LAMMPS requires PBC in all ...
user6363's user avatar
2 votes
0 answers
34 views

Literature applying molecular docking into MD-simulated structures of proteins

This is quite surprising, at least for me, that many papers performed molecular docking of an unsimulated (original) protein structure and MD simulation of a protein in a timescale to check the ...
làntèrn's user avatar
  • 231
2 votes
0 answers
44 views

Appropriate choice of force constant of spring to use for Steered molecular dynamics

As per Boltzmann distribution, the variance, or the fluctuation in length squared is given by $$\sigma^2 = \frac{k_BT}{k_{spring}}$$ Since $k_{spring}$ determines how strong the force I am applying to ...
Roshan Shrestha's user avatar
2 votes
0 answers
96 views

Re-parametrization of force fields in LAMMPS

I am interested in trying to re-parametrize existing force fields in LAMMPS (let's say ReaxFF or MYP0) but I am not able to find any clear tutorial or information on how to do so. Do you know of good ...
Paul Logan's user avatar
1 vote
0 answers
23 views

LBFGS -- Incomplete Convergence due to BadIntpln

I am doing energy minimization of a molecular system in TINKER. While doing so, I am getting the error in the title of this question. What might be my problem?
Himanshu's user avatar
1 vote
0 answers
48 views

Free energy calculations for lammps

Is there any tutorial or reference available to perform free enegy calculations (umbrella sampling; thermodynamic integration; free energy perturbation; widom's particle insertion method) etc. With ...
Robin's user avatar
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1 vote
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When optimizing AMBER molecular dynamics parameters for protein-ligand interactions, how do I balance accuracy and efficiency?

Are there established practices for fine-tuning AMBER MD parameters in scenarios like mine, involving specific factors like mutant proteins or non-standard ligands? Has anyone successfully tackled ...
Don Aborah's user avatar
1 vote
0 answers
12 views

What are the appropriate boundary conditions for simulating shear deformation of a screw dislocation in LAMMPS?

I'm seeking clarification on the selection of suitable boundary conditions for simulating shear deformation of a screw dislocation using LAMMPS. In my script, I currently employ the following commands:...
Vikram Roy's user avatar
1 vote
0 answers
55 views

Where should we compute `Energy` in this listing?

Cross-posted here. I have the following listing for a barebone MD simulation: ...
user366312's user avatar
  • 2,352
1 vote
0 answers
27 views

Adaptive Biasing Force Simulations in NAMD

I have performed an ABF simulation to investigate the binding of a small molecule with a 2D surface using NAMD. The initial simulation was for a scan window of 3 to 15 angstroms of z-projected ...
Hemanth Haridas's user avatar