# Questions tagged [cp2k]

For questions about (or related to) the software CP2K.

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### CP2K geometry optimization SCF takes 3000s for a step

I am new to CP2K and doing a geometry optimization for a cluster. At the beginning everything looks good, each SCF step takes about 13 seconds, the energy drops quickly and the convergence looks like ...
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### total force calculated with cp2k not zero

I performed DFT calculations for a box of 64 water molecules under Periodic Boundary Condition using CP2K. I found that the forces on each atom do not sum up to zero, as shown in the attached figure. ...
• 273
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### Calculate Hessian for configurations that are not at the minimum of the Potential Energy Surface

I want to calculate the Hessian matrix for molecular configurations that are not at the minimum of the Potential Energy Surface, using cp2k. But it seems that cp2k requires the configuration to be ...
• 273
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### How to run 2nd generation CPMD in CP2K?

I believe CP2K by default implements Born–Oppenheimer MD. I have seen many recent papers that use 2nd generation Car–Parrinello MD using CP2K. But I couldn't find any direct way of switching to 2nd-...
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### Setup for 4-point flexible water model [closed]

I tried to search online if there are examples or suggestions on how to set up a 4-point flexible water model, such as TIP4P/2005f, qTIP4P/f, TIP4P/$\epsilon$ FLEX, etc., but there's no clear example ...
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### Molecular dynamics to reproduce dispersion interactions [closed]

I'm trying to simulate the behavior of chromophore molecules incorporated into a polymer under an external electric field. I've tried to use classical molecular dynamics (GROMACS) but it's unable to ...
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### What is a "charged system" in this specific context?

I'm doing a polarization calculation for the first time. To specify one of the input parameters (the "reference point") correctly, I have to figure out if my system is "charged." ...
• 707
42 views

### Kinetic energy cut-off for Gaussian-type orbitals when applying periodic boundary conditions [duplicate]

I have a solid with PBC (periodic boundary conditions) and I want to perform a DFT simulation. I use GTO as the basis. In a paper I read, I can transform the GTO to a Bloch function (crystalline ...
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### Reading complex potential into CP2K

Is it possible to read a complex potential into CP2K? I have generated a potential using FDTD at a given frequency, which results in a complex result. The potential is to be read in to a real time ...
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### CP2K Spherical Cell [closed]

I'm trying to run a gas phase cluster calculation in CP2K. I want to create an outside force to constrain water molecules that are in the simulation within a radius of a central ion. I want to create ...
• 71
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### cp2k conserved quantity changed when restart NVT MD?

The details are descripted elsewhere, but got no answer for days, so I post it here for help. As title said, I noticed a relatively big change in conserved quantity and don't know why. I've upload ...
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163 views

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

CP2K implements the Gaussian and Augmented Planewaves (GAPW) approach for all-electron calculations. My understanding is that the GAPW method involves using atom-centered Gaussian type orbitals to ...
• 613
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### Periodic polarizable QM/MM embedding [closed]

Are there any standalone open source software codes available for periodic polarizable QM/MM embedding MD simulations? In my knowledge, CP2K only has the option for electrostatic embedding and other ...
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### Failure of CP2K density functional software to converge for a 64 Si atom amorphous structure

The structure was created using Stillinger Weber with LAMMPS. The command I used was the following: ...
• 81
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### CP2K vs BigDFT comparison [closed]

I typically run DFT calculations with 1000 to 5000 atoms using CP2K. This works fine but I'm interested in BigDFT also. Is there anyone here that has experience using BigDFT and is able to compare ...
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### Is there any reason not to sum the kinetic and potential energy from an NPT simulation to get internal energy?

I would be very grateful for some newbie-level advice from a thermodynamics guru. I ran NPT simulations on a particular system (in CP2K software) to get fluid densities for use in fluid dynamics ...
• 707
215 views

### What are some methods for modeling bulk phase infrared spectra?

I am interested in predicting the infrared spectra of bulk phase molecules, it seems that AIMD (ab initio molecular dynamics) is the current best approach. I have found a tutorial on using CP2K to do ...
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### Is it possible to use the Parrinello-Rahman barostat for NPT simulations in CP2K?

It is possible to use different types of thermostats in CP2K by specifying them in the corresponding section of the input as mentioned here. But there is no mention of specifying the barostat type in ...
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