From NWChem
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| 1:33:43 PM PST - Mon, Feb 4th 2013 |
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| The NWC 6.1 documentation says that the default # of iterations for a DFT job is 30. However, several of my recent B3LYP jobs using version 6.1.1 (Jan 2013) have stopped at 20 iterations with a "not reaching convergence" message. Is it 20 or 30?
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Edoapra Forum:Admin, Forum:Mod, bureaucrat, sysop
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| 6:13:34 PM PST - Mon, Feb 4th 2013 |
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Jwkeller,
The default limit for the number of SCF iterations in the DFT module has not been changed from 30 in NWChem 6.1.1.
You can check the value for your run by searching for the string "Maximum number of iterations", as in the example below
Maximum number of iterations: 30
The only case when NWChem could bail out prematurely (before having reached the 30 cycles limit) is when you are running
under a jobs queuing system (e.g. PBS, LSF, Slurm). If 1) a jobs queuing system is present and 2) NWChem has been configured to detect the wall-time limit during the execution inside the queuing system, then a NWChem job can stop before the 30 cycles limit has been reached, after NWChem has projected that it will run out of time.
Cheers, Edo
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| 11:29:50 AM PST - Tue, Feb 5th 2013 |
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Sorry, I confused "iterations" with "steps". Each optimization step includes up to 30 iterations to optimize the MO coefficients in creating a self-consistent field. I am concerned rather with how to control the number of geometry optimization steps (nptopt). The output.out file states "maximum number of steps (nptopt) = 20", and the geometry optimization is stopping there without attaining a geometry optimum. How do I set nptopt = 50, say? (as in gaussian, opt = maxcycles = 50).
Quote:Jwkeller Feb 4th 12:33 pmThe NWC 6.1 documentation says that the default # of iterations for a DFT job is 30. However, several of my recent B3LYP jobs using version 6.1.1 (Jan 2013) have stopped at 20 iterations with a "not reaching convergence" message. Is it 20 or 30? |
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Edoapra Forum:Admin, Forum:Mod, bureaucrat, sysop
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| 11:18:11 AM PST - Wed, Feb 6th 2013 |
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Quote:Jwkeller Feb 5th 10:29 amSorry, I confused "iterations" with "steps". Each optimization step includes up to 30 iterations to optimize the MO coefficients in creating a self-consistent field. I am concerned rather with how to control the number of geometry optimization steps (nptopt). The output.out file states "maximum number of steps (nptopt) = 20", and the geometry optimization is stopping there without attaining a geometry optimum. How do I set nptopt = 50, say? (as in gaussian, opt = maxcycles = 50).
Somewhere above the "task optimize" section, and below the "geometry" section, put a section with the heading "driver" and various entries under that, followed by "end". The entry that adjusts the maximum number of geometry optimization steps, n, is "maxiter n". This is also the section where "loose", "tight", or detailed energy criteria for convergence can be inserted.
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