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Questions tagged [geometry-optimization]

Questions about finding the molecular or material geometry that has the lowest energy.

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9 votes
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How does the line search in geometry optimisations work?

I am trying to write a Newton-Raphson geometry optimisation script in python (Current version of my code) using the energy, gradient and Hessian from Gaussian 16. In order to reach a minimum, I would ...
evd's user avatar
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7 votes
0 answers
83 views

Correct method for structure optimization using DFT tools

Lets's say I want to start off DFT calculations for a material whose experimental cell constants are known. So I have two ways to get the correct structure to later on calculate, say, band structure ...
AbPhys's user avatar
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6 votes
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84 views

Spin-orbit coupling(SOC) in geometry optimisation

When I tried including SOC during the optimization of InBi lattice constants, the lattice constant increased from 4.6 Å (without SOC) to more than 6 Å (with SOC), which seems like an 'incorrect' ...
James's user avatar
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5 votes
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213 views

Help regarding Geometry Optimization of a bimetallic surface

I am trying to perform a geometry optimization (GEO_OPT) of a FCC 111 Pt$_{0.5}$Au$_{0.5}$ bimetallic surface (10x10x3) generated from ASE, with a lattice parameter of 3.9 $\overset{\circ}{\mathrm{A}}$...
ARKA PRAVA SARKAR's user avatar
4 votes
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What software is fit for calculating an atomic and electronic structure of a newly formed nanocluster after injecting impurities into an initial one?

Let's suppose there is a nanocluster and its structrure is known. The problem is to inject impurities into this nanocluster. The impurities can be injected in different quantitites but consist only of ...
SFriendly's user avatar
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4 votes
0 answers
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Consequences of starting a new relaxation calculation from the final coordinates of an interrupted run

In order to address oscillating total force during an ongoing relaxation calculation in Quantum ESPRESSO, I've found it effective to interrupt the current run and commence a new relaxation calculation ...
Joyal sunny's user avatar
4 votes
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31 views

Incorporating Phonon Calculations as a Criterion for Geometrical Relaxation

In the context of first-principles calculations, such as DFT, lattice vibrations are often determined through phonon calculations, providing valuable insights into the stability and dynamics of ...
Jaafar Mehrez's user avatar
4 votes
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56 views

How to compute only part of molecular Hessian accurately (hybrid Hessian or partial Hessian calculation)?

Hessian is required for minimisation and transition state (TS) optimisation algorithms. While the full Hessian at a certain level of theory is calculated usually for TS optimisation, usually ...
S R Maiti's user avatar
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3 votes
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32 views

Which is the best way to plot E_tot vs Lattice graph for structures with two lattice parameters?

I made the graph using the ratio between the parameters x E_tot (trigonal structure), but I would like to know if there is a better way to do this.
Gabriel Elyas's user avatar
3 votes
0 answers
30 views

Constrained geometry optmization: Molecule interacts with its surroundings

I have a water cluster(suppose) generated from MD run. Now, I want to optimize the geometry of only one water molecule of interest using QC methods (e.g. B3LYP/6-31+G(d,p)). I intend that the water ...
Pro's user avatar
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3 votes
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Discrepancy between Force Convergence in Geometrical Optimization and SCF Calculation in VASP: Reasons and Troubleshooting Suggestions

During a geometrical optimization of ions and lattice parameters in VASP, the forces acting on atoms were minimized to less than 0.01 eV/Å. However, when performing the subsequent self-consistent ...
Jaafar Mehrez's user avatar
3 votes
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154 views

Quantum Espresso optimization calculation not converging

I have been trying to optimize the geometry of a copper based metal halide perovskite. I opened the CIF file using BURAI GUI and generated the VC-RELAX input file. I have increased the steps to be 200 ...
Kamal Nassar's user avatar
2 votes
0 answers
68 views

Different QM and MM gradients in geometry optimization

I calculated the single point energy of some small molecule using the PM7 method (with COSMO solvation model) in MOPAC and calculated the gradients. Then I calculated MM potential energy with ...
klani's user avatar
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2 votes
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122 views

Prerelaxation before AIMD with VASP

I am investigating a bulk structure by ab initio molecular dynamics (AIMD) implemented in VASP. I was wondering, how to choose the initial geometry (= POSCAR file) to run the AIMD simulation. In the ...
Lukas's user avatar
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2 votes
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75 views

Wrong lattice parameter of CeO2 after structure relaxation with VASP

I am calculating the lattice parameter of CeO2 with VASP, but the optimized lattice parameter is wrong according to many references (Physical Review B 75, 035109 (2007); The Journal of Chemical ...
FaDA's user avatar
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1 vote
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35 views

How can i do a variable cell relaxation under the influence of constant field in GPAW?

As a continuation of my previous question, I would like to do variable cell relaxation of BaTiO3 under the influence of a constant electric field. The script I've used is given below: ...
Atom's user avatar
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1 vote
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21 views

Optimization error in quantum dot graphene doping with antimony atoms

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fatemeh's user avatar
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1 vote
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96 views

Disappearing vacuum layer when relaxing bilayered hBN with VASP

I'm doing geometry optimization of bilayer h-BN, a 72-atom supercell (6x6x1) with vacuum thickness of 20 Å, and I set the parameters in INCAR as below: ...
Meifeng WANG's user avatar
1 vote
0 answers
114 views

Structural phase transition under uniaxial strain

I am trying calculate a strain-induced phase transition in some weakly correlated crystalline material using Quantum ESPRESSO (QE). The compound has two (experimentally observed) phases, one of which ...
manju9's user avatar
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