From owner-chemistry %-% at %-% ccl.net Mon Jan 3 09:05:00 2022 From: "Detlev Conrad Mielczarek detlevcm~!~googlemail.com" To: CCL Subject: CCL:G: Estimated job time in Gaussian Message-Id: <-54567-220103052832-828-YdLAKeclsz81pc6UEe4i3A a server.ccl.net> X-Original-From: Detlev Conrad Mielczarek Content-Language: en-US Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=UTF-8; format=flowed Date: Mon, 3 Jan 2022 11:28:20 +0100 MIME-Version: 1.0 Sent to CCL by: Detlev Conrad Mielczarek [detlevcm_._googlemail.com] Estimating compute times is its own area of research and typically very hard to do - not just in ab initio quantum chemistry but also in other fields, say CFD. Under certain circumstances, it is possible to look at the time used for the initial iterations and thus extrapolate the required time for a set number of iterations to get a rough idea. E.g. if I know I complete 200 CFD iterations a day, I will possibly do 1000 in 5 days. Having said that, CFD convergence is possibly a lot more straightforward than ab initio calculations. Just the choice of method and basis will have a dramatic impact on the calculation time. Then small perturbations in the starting geometry can equally impact the calculation time for more complex geometries as its can impact the trajectory selected during the optimization. For very simple molecules, it may be possible to establish correlations and thus make accurate predictions, but these simple molecules will either require seconds (for teaching purposes with simple methods and small basis sets) or be subject to very high accuracy calculations in research where time matters less. Still, this could be a subject for a research project... Detlev ORCiD 0000-0002-4720-353X On 31/12/2021 23:14, Andrew DeYoung andrewdaviddeyoung*gmail.com wrote: > Sent to CCL by: "Andrew DeYoung" [andrewdaviddeyoung\a/gmail.com] > Hi, > > Does anyone know if it is possible for the Gaussian package to estimate the > time remaining in a relatively pedestrian calculation (e.g., Opt Freq)? I'm > not seeing a discussion of this in the documentation. I'm running Gaussian > 2016 (G16). > > Thanks in advance for any insight you can provide, > > Andrew > > Andrew DeYoung, PhD > Department of Chemistry > Carnegie Mellon University > andrewdaviddeyoung###gmail.com> >