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16

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 for geometry optimization. Maybe the documentation should have said "optimization algorithm" instead of "optimizer", to make this more clear: ...


14

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 potential energy surface. However, optimizers can also be used in other areas in DFT, for example, to optimize the wavefunction. Below I will give a brief ...


10

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.


8

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 the conclusions: Starting from the GPW approach we substituted the PW auxiliary basis for the electron density by an APW auxiliary basis which besides plane ...


6

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 valuable and useful property. You are also correct that the internal energy is the summation of potential and kinetic contributions. To be thorough, pp. 60 of ...


4

In the input file you define &THERMOSTAT &CSVR TIMECON 9.9999999999999986E+01 &END CSVR &END THERMOSTAT So I guess you intended to use the CSVR (canonical sampling through velocity rescaling) thermostat. But because you did not set TYPE CSVR CP2K uses the default Nose Hoover thermostat instead. However, CP2K does not save ...


4

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. The modified file is: &FORCE_EVAL METHOD QUICKSTEP &DFT BASIS_SET_FILE_NAME ./BASIS_SET POTENTIAL_FILE_NAME ./GTH_POTENTIALS &QS EPS_DEFAULT 1E-10 &...


4

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 applying laser pulses and that you should use EXTERNAL_POTENTIAL instead, with the READ_FROM_CUBE option. Not sure whether printing the imposed potential is possible, but you could print the ...


4

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 faster), obtaining vibrational densities of state and use vibrational maps to scale the VDOS spectra appropriately. Many researchers also simply calculate ...


3

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 electronic structure methods in general is to combine calculations on fragments to approximate an electronic structure. John Herbert's Group is doing work in ...


3

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. 14 OT DIIS 0.15E+00 0.4 0.00000001 -250.3728024712 -3.24E-11 15 OT DIIS 0.15E+00 0.4 0.00000001 -250.3728024712 -2.69E-11 16 OT DIIS ...


2

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 default length unit seems to be angstroms, so the density matrix elements are likely in angstroms$^{-3}$. From the CP2K Documentation the E-Field is given in units ...


1

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 corresponding PARAMETERS of your potential has to be real. I don't know anything about the internal code of CP2K, so I don't know if this would be a simple modification of the code to accept complex ...


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