[CP2K-user] [CP2K:18229] Re: How to Gaussian type calculations and Performance

DMT dobromirak at gmail.com
Tue Dec 20 14:15:17 UTC 2022

Dear Marcella,

!!!> Yes, I had posted the wrong input file. Now I am attaching the real 
one + the output.

Thank you for clarifying the MIXING option.

On an average a single micro-iteration takes 6.2 seconds, the total number 
of micro-iterations for convergence is 33.

The first 11 subroutines seem to take the most time:

 CP2K                                 1  1.0    0.046    0.046  210.153 
 qs_energies                          1  2.0    0.000    0.000  209.392 
 scf_env_do_scf                       1  3.0    0.000    0.000  208.603 
 scf_env_do_scf_inner_loop           33  4.0    0.002    0.002  208.603 
 qs_ks_update_qs_env                 33  5.0    0.000    0.000  182.059 
 rebuild_ks_matrix                   33  6.0    0.000    0.000  182.057 
 qs_ks_build_kohn_sham_matrix        33  7.0    0.003    0.003  182.057 
 hfx_ks_matrix                       33  8.0    0.000    0.000  110.000 
 integrate_four_center               33  9.0    1.361    1.361  109.993 
 integrate_four_center_main          33 10.0    0.180    0.180  106.232 
 integrate_four_center_bin         1610 11.0  106.052  106.052  106.052 

the rest take below 30 average total time.

As for the column ASL, the largest are:
pw_scatter_s                       562 13.2<-ASL (the second number)
fft3d_s                           1134 12.7
fft_wrap_pw1pw2_200                597 11.9
integrate_four_center_bin         1610 11.0
xc_pw_derive                       198 11.0
fft_wrap_pw1pw2                   1133 10.7
integrate_four_center_main          33 10.0
xc_rho_set_and_dset_create          33 10.0
xc_pw_divergence                    33 10.0
On Tuesday, December 20, 2022 at 3:36:27 PM UTC+2 Marcella Iannuzzi wrote:

> Dear Dobomir,
> The posted input refers to a pseudo potential calculation using GPW and 
> not to an ALL electron calculation using GAPW. 
> In this case the total energies of Gaussian and CP2K are not comparable.
> But maybe you posted the wrong file. 
> Anyway, for molecules please remove the Broyden mixing, which is a G-space 
> mixing. 
> Concerning the timings, is the single iteration time too long or the 
> number of iterations to convergence too large?
> In the final timings written in the output it is possible to check which 
> part of the calculation is taking large portion of the allocated resources. 
> Kind regards
> Marcella
> On Tuesday, December 20, 2022 at 2:01:25 PM UTC+1 DMT wrote:
>> Hello,
>> I am new to CP2K and this is my first post in the group. I have heard 
>> many positive things about the program and I want to study it. First I want 
>> to learn how to do the kind of calculations I am already used to use other 
>> software for.
>> I have several questions and I'm mainly interested in organic systems.
>> I picked a very simple metalo-organic complex for test of accuracy, 
>> properties and speed (my resources are not unlimited).
>> The Gaussian calculation I chose to repeat is very simple - Single Point 
>> (Energy run) with m062x functional and def2-tzvp basis set. I used the CP2K 
>> Energy tutorial and managed to put together the attached input file.
>> To my understanding I have to use QS > METHOD GAPW in order to apply the 
>> basis set, which I downloaded in CP2K format from the Basis Set Exchange 
>> web site.
>> Since the system is not PERIODIC I used POISSON_SOLVER WAVELET.
>> I also left MIXING T and used BROYDEN_MIXING with ALPHA 0.4 (default) and 
>> NBROYDEN 8 (from input examples).
>> I assume in MGRID: NGRIDS 5 and CUTOFF 400 are good values (from other 
>> inputs)
>> In the &XC_FUNCTIONAL I used &HYB_MGGA_X_M06_2X and in the &HF section I 
>> placed FRACTION 0.54 (54% HF Exchange is the default in m062x).
>> In the KIND X sections I wrote BASIS_SET def2-tzvp and POTENTIAL ALL, 
>> which to my understanding forces no core potential at all, but instead uses 
>> all electrons from the basis. I noticed that in the &DFT section I had to 
>> place POTENTIAL_FILE_NAME POTENTIAL, because although I'm not using a 
>> potential CP2K gives an error if I don't provide a potential file. I took 
>> the file from the "data" dir of the cp2k source code. <<< Is this the 
>> correct way to do it, when there is no potential ?
>> My ABC setting in &CELL is 12 12 12, although the system is quite a bit 
>> smaller in distances between nuclear coordinates - otherwise I get a 
>> warning about density at the box edges and convergence is even slower.
>> Are those setting fine, if I simply want to repeat a Gaussian SP job for 
>> testing ? Have I picked the DFT functional correctly ? How about the HF 
>> part ? Can you tell me in short what exactly is this MIXING and when to use 
>> it ?
>> CP2K performed quite a few times slower than Gaussian (about 10x). I 
>> don't want to state the exact timings (I checked with the command `time'), 
>> because Gaussian License prohibits publishing of timing information.
>> Without the &HF section the performance increases 2x to 3x, but I guess 
>> that is for the lack of HF Exchange, which simply makes m062x wrong. The 
>> Energy without HF Ex is considerably higher. Wither way Gaussian gives a 
>> much lower result for the total Energy. What is going on and am I doing it 
>> the right way ?
>> I understand CP2K has its strengths and in no way I want to speak against 
>> it, I just want to learn how to use it and before I get into PERIODIC 
>> systems, surface interactions / reactions, solvents and molecular crystals 
>> (where I bet CP2K is much better than Gaussian) I want to learn the basics 
>> and repeat the kind of calculations I am used to.
>> Any comment can be of help. Anything to get to a well done calculation 
>> and with an increased performance, without sacrificing accuracy too much.
>> Best Regards,
>> Dobromir

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