16 votes
Accepted

What exactly is the "Optimizer" in CP2K geometry optimization?

The question says: I am having trouble understanding the difference between the optimizer options (CG, BFGS, LBFGS). These are three optimization algorithms that evidently are implemented in CP2K ...
Nike Dattani - No Free Time's user avatar
14 votes

What exactly is the "Optimizer" in CP2K geometry optimization?

Optimizer refers to the algorithm used for finding the minimum of a function. In this specific case the optimizer is referring to "geometry optimization" which seeks to find the local minimum of the ...
Cody Aldaz's user avatar
  • 8,017
10 votes
Accepted

Is it possible to use the Parrinello-Rahman barostat for NPT simulations in CP2K?

The barostat used by CP2K is the one developped by Glenn J. Martyna et al. J. Chem. Phys. 101, 4177 (1994). The Parrinello-Rahman barostat is not implemented in CP2K.
Fabian's user avatar
  • 1,421
9 votes
Accepted

Total force calculated with cp2k not zero

There are generally two main reasons why the total force can be nonzero (in any DFT code): Your forces are only correct when the calculation has converged fully to the ground state, and so in ...
Phil Hasnip's user avatar
  • 7,262
9 votes
Accepted

Is basis set superposition error reduced when using the GAPW method?

Short answer: no. The idea of the GAPW method described in Theor. Chem. Acc. 103, 124 (1999) is simply to speed up the evaluation of the Coulomb and exchange-correlation contributions. Quoting from ...
Susi Lehtola's user avatar
  • 19.1k
8 votes
Accepted

SCF energy keeps on fluctuating between two values, instead of converging, why?

The cause of the oscillations in the SCF energies is probably a "sloshing instability"; the two most common types are "charge sloshing" and "occupancy sloshing". Sloshing ...
Phil Hasnip's user avatar
  • 7,262
8 votes
Accepted

Is there any reason not to sum the kinetic and potential energy from an NPT simulation to get internal energy?

Energy in an NPT simulation is not conserved, but (once equilibrated), it will fluctuate around an average value, and that average value has meaning. That is the ensemble average for your NPT and is a ...
B. Kelly's user avatar
  • 4,366
6 votes
Accepted

Calculate Hessian for configurations that are not at the minimum of the Potential Energy Surface

It is difficult to understand what you mean by "correct" answer, especially when we are discussing a "not-geometrically-optimized configuration" as you have called it, so I will ...
Elie H's user avatar
  • 1,412
5 votes

Ab-initio molecular dynamics of liquid systems: best tools and resources

CP2K CP2K is an open source electronic structure and molecular dynamics software package to perform atomistic simulations of solid-state, liquid, molecular, and biological systems. It is especially ...
Hayden S's user avatar
  • 930
5 votes

How to run 2nd generation CPMD in CP2K?

A similar question has been asked on the cp2k mailing list. The relevant settings are the MOTION / MD / ...
leopold.talirz's user avatar
5 votes

Calculate Hessian for configurations that are not at the minimum of the Potential Energy Surface

The Hessian at a non-stationary point is well-defined, since it is the second derivative of the energy wrt. nuclear coordinates. The transformation to vibrational normal coordinates, however, assumes ...
Frank Jensen's user avatar
  • 1,776
5 votes

Calculate Hessian for configurations that are not at the minimum of the Potential Energy Surface

You could in principle compute the entire Hessian for any configuration of a molecule. The problem is that we are typically not interested in the entire Hessian: we want the Hessian for the internal ...
Tyberius's user avatar
  • 15.5k
4 votes
Accepted

Geometric optimization taking a long time. Are my convergence criteria too tight in CP2K?

After a bit of hit and trial, I am able to run the pyridine sample, using CP2K v7.0 (git:d15a9c53f), however I think this can be run on any CP2K version beyond v2.5....
mykd's user avatar
  • 2,292
4 votes

Reading in E-field with CP2K

From looking at the very long wavelength you specified, I assume your intent is to apply a static field to the calculation? I read here that EFIELD is intended for ...
leopold.talirz's user avatar
4 votes
Accepted

What are some methods for modeling bulk phase infrared spectra?

Vibrational maps and density of states In water AIMD community, to avoid excessively heavy calculations of molecular moments, researchers use velocity autocorrelation function (which converge much ...
mykd's user avatar
  • 2,292
4 votes
Accepted

cp2k conserved quantity changed when restart NVT MD?

In the input file you define &THERMOSTAT &CSVR TIMECON 9.9999999999999986E+01 &END CSVR &END THERMOSTAT So I guess you intended ...
Fabian's user avatar
  • 1,421
3 votes

Can CP2K be used for slab calculations?

CP2K employs Gaussian basis sets and can do 3D (crystals), 2D (slabs), 1D (wires) and 0D (atoms and molecules) periodic calculations naturally, without inducing fictitious interactions of periodic ...
Susi Lehtola's user avatar
  • 19.1k
3 votes
Accepted

Model coordination complex using GROMACS or CP2K

Here is how you can get the structure from PubChem, read the SMILES into Avogadro2, do a MMFF94 (classical) optimization, and then a single-point energy calculation using NWChem (RHF, 6-31G*). The ...
Todd Minehardt's user avatar
3 votes

What is a "charged system" in this specific context?

I have not used CP2K, but based on the documentation, this should refer to the charge of the whole system. So if you don't have a reason to believe your system is charged, you should treat it as ...
Tyberius's user avatar
  • 15.5k
3 votes

What are some methods for modeling bulk phase infrared spectra?

I'm not an expert in MD/AIMD software so I can really only discuss methods rather than an actual workflow/software that can carry it out. One approach that has been explored for accelerating AIMD and ...
Tyberius's user avatar
  • 15.5k
3 votes

Failure of CP2K density functional software to converge for a 64 Si atom amorphous structure

After modifying your file, I was able to get a converged energy of -250.37 hartrees, using CP2K v7.0 `(git:d15a9c53f), however I think this can be run on any CP2K version beyond v2.5. ...
mykd's user avatar
  • 2,292
2 votes

What are the default units for the core hamiltonian and the density AO matrices in CP2K?

I have yet to find an explicit place where this is stated in the documentation, but the default unit for energy, and thus the core Hamiltonian, seems to be a.u., that is, hartree. Similarly, the ...
Tyberius's user avatar
  • 15.5k
1 vote

Reading complex potential into CP2K

If I'm interpreting the manual correctly, it is not possible to define a complex external potential in CP2K. It specifies that the VALUES keyword to define the ...
Tyberius's user avatar
  • 15.5k

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