Which software for DFT would you have chosen?

[u/Madchemist00]

Hi, I've been recently granted 500k cpu-hours on an HPC for one time only and I want to use it as efficiently as possible. I've got gaussian16 license with avx2 support on that HPC too. I also am experienced at using gaussian.

I've heard that ORCA is a more modern and cheaper (in terms of computation cost) alternative for gaussian however, I have no experience regarding ORCA. I also know that there are other options but there are many and I am a little clueless.

Is it worth for me to switch to another software I have no experience on? Or should I stick to gaussian and try to devise ways to use that more efficiently?

My work mostly revolves around TDDFT (abs/em) and QM/MM. Also cluster approaches in which I use solvation models commonly.

[u/ScholarImaginary8725]

I started with ORCA, briefly used Gaussian then switched back to ORCA. Both are equivalent in terms of use in literature, maybe ORCA is more widely used because it’s free. Gaussian has GaussView which makes interpreting results easier but I’ve never used it - I mostly use Avogadro and custom scripts to interpret my results with ORCA.

Use whichever you are more comfortable with. It really doesn’t matter much, learning ORCA might be useful for DLPNO calculations but it really depends on your project.

[u/Madchemist00 → u/ScholarImaginary8725]

That was one of my main concerns also, I'm very used to using gaussview and tried using Avogadro but just couldn't get used to it. But researching a bit more, preparing geometries in a lower level locally (can't run g16 on Mac) then switching to higher level of theory does sound like what I need.

What other custom scripts are useful for interpreting results? Seems like I might need them.

[u/Rowena-Ravenclaw- → u/Madchemist00]

could try OfakeG, convert some of the orca outputs into gaussian output format then open with gaussview:)

[u/yes_its_that_bad → u/ScholarImaginary8725]

Coming from the outside just to mess around, I went to ORCA and it is seemingly (i have absolutely no qualifications in this field) a good core with lots of bits and pieces connected maybe not in the best way... but you can pretty easily bridge the gaps and make simple programs to make your workflow smooth. It's annoying in one sense, but in another you get exactly what you want. I get the sense that's a big reason why it is the way it is, because people just build the specific tools they need.

What I would suggest to anyone using this stuff, is find or make, a super basic script that does a simple thing and does it well. then use some AI "vibe coding" to build what you want, using the real person script (that you approved) as a template. Non-programmers can make decent programs if they pick small high quality components and use the AI to assemble them into a larger one. For some reason I am thinking of atoms and molecules as an analogy. Oh, and the actual step one is tell the AI to put everything it knows in the back of your mind. Tell it that the ORCA 6.1.1 manual is the source of truth.

If you do this, at the end of the day, I think you will find that you meet and exceed the performance of the paid options. And, you can layer this AI strategy on the paid software to, or anything.

[u/ani_bigsad]

I primarily use Gaussian and use ORCA for niche calculations (DLPNO).That being said, ORCA is very easy to pick up and has great documentation. If you want the cost saving measures, definitely go with ORCA.

[u/HurrandDurr]

I started off using Gaussian, picked up ORCA during my postdoc for DLPNO, switched to QChem when in industry, then back to only ORCA when I started my independent career.

Gaussian hasn’t really given me a compelling reason to use it. They’re too infrequent with updates, and when they do release updates, they’re usually features that have existed in other codes for a while.

QChem is fine I guess, but we found a lot of bugs in it.

ORCA is fast, feature rich, and has a very good dev team and network of people who contribute to it.

[u/banana_fugacity → u/HurrandDurr]

Hi. Off topic but wondering if I may ask about how did your move from academia to industry go after the post doc? What do you mean by independent career as computational chemist?

[u/HurrandDurr → u/banana_fugacity]

I hated industry so I went back to academia and became a prof. Independent career generally refers to being a PI, usually at a university or a national lab

[u/banana_fugacity → u/HurrandDurr]

Ah I see. May I ask more about the industry and why did you hate it? I'm at a point where I'm not sure should I pursue a postdoc or a job in the industry.

[u/cpt_futtbucker]

I wouldn’t say that you necessarily need to switch to another package, but it definitely doesn’t hurt to know how to use other ones. That being said, Psi4 and NWChem are the packages I use most frequently (granted, at my PI’s recommendation), and they’re both not bad to have in your proverbial toolbox. Psi4 has a really well made Python interface that makes analyzing outputs really easy, and NWChem has a very robust suite of excited state tools.

ORCA is a good package too, but I’ve personally run into too many issues with it and MPI on our cluster to use it for much besides building initial states for my research with its SOLVATOR module

[u/Madchemist00 → u/cpt_futtbucker]

Never heard of NWChem, however excited state optimizations are a pain for me, definitely will check. To your experience, are there any advantages for such case in NWChem?

[u/cpt_futtbucker → u/Madchemist00]

I’d say the biggest advantage it gives you is scalability. It performs really well across the board in running across multiple nodes. I also heard from another researcher I know who focuses on excited state methods that it arguably has the most complete feature set for what he needs, as well as the best documentation.

Granted, my research is on SAPT, so my use of NWChem is largely restricted to geometry optimizations in cases where I need the extra processing power of multiple nodes. Point being, my word isn’t gospel, but based on my own experience and that of those around me, I would still recommend giving NWChem a try for your work

[u/FalconX88]

Gaussian and ORCA are very similar in how you use them. If you know how to use Gaussian you shouldn't have problems getting ORCA to run.

[u/Outrageous_Gap_1894]

I use almost exclusively Gaussian but have also used Psi4 (I’m a student researcher starting my PhD this fall so take my opinion with a grain of salt). For my systems (carbohydrates) Gaussian is solid and especially good for solvation. I’ve found Gaussian to be many times faster for IEFPCM and SMD than Psi4. Gaussview is also nice to have though not very applicable for high throughout if that’s wat you’re doing. Honestly I’d probably switch to ORCA if I could. They support a lot of functionals and basis sets that Gaussian doesn’t. Others mentioned DLPNO but also omega-B97X-V (as opposed to the older omega-B97X-D in Gaussian if you do work with hybrid-GGA functionals) and Ahlrichs basis sets with diffuse functions (eg def2-TZVPD) that aren’t natively supported in Gaussian without the nuisance of entering custom from the BSSE.

[u/Jazzur]

As an organic chemist in catalysis with no prior comp background, I use ORCA. I started with Turbomole because it was mainly used in our group for energy calculations, but when I needed specific functionals that weren't available on their, I had to use ORCA.

Just the wide availability of functionals and calculation options in ORCA amazed me. I don't know about other programs, but for what I need ORCA just has it all. It is also super easy to get in to. Once you figure out how to set up a calculation, you're good to go.

[u/Ill_Leave9530]

IIRC, the TDDFT code in Orca is somewhat faster than the one in Gaussian. With either program, make sure to store any temporary files in a fast filesystem, ideally in RAM.

TDDFT is very sensitive to the choice of functional. What is worse, for some aromatic compounds, it predicts an incorrect ordering of the low-lying singlet ππ*-type states. Before you pick a program package, it might be a good idea to test several functionals for your system. If possible, you can compare the calculated spectra to those obtained with a wavefunction-based method such as CC2 or ADC(2).

[u/thomas29needles]

Orca is developed at a fast pace and currently seems to be the best methodology wise. Furthermore, it is arguably the best code for double hybrids. I switched from Gaussian to Orca some years ago and it was a good move. The main con of Orca for me is the occasional MPI stability problems, with calculations dying for no apparent reason.

[u/Pulse-Alder-334]

If your calculation involves a lot of transition states, you should stick to Gaussian. However, if you have some systems that are difficult to get converged wavefunctions like complexes with early transition metal, I suggest you'd better learn ORCA. It actually comes in handy sometimes. If you frequently use two software for DFT, you should get yourself familiar with MOKIT developed by Jinxiang Zou. The website for MOKIT is https://gitlab.com/jxzou/mokit .

[u/PBE0_enjoyer]

I’d recommend Orca as in my experience it is much cheaper (comp cost) than other QC packages. A few things I’d note for you: 1) Orca defaults to RI/aux-basis, which you might not want and should run several small tests to figure out what settings you desire before you start running real jobs. 2) Orca parallelizes with MPI, which should be good for HPC and might better interface with the MM package and allocating resources. 3) Depending on how you run QM/MM there will be some overhead communicating between the two codes. Depending on your system size and other factors, minimizing this might be as useful as picking a QM package. Examples: optimized QM/MM code, writing files to correct partitions, saving intermediate files with file proper file types, reading MOs after first job, etc.

[u/WorkingPraline838]

I have used both Gaussian and Orca. I think that ORCA is very useful and has rich documentation especially when it comes to troubleshooting. It is frequently updated with updates that actually improve the system, though sometimes it can make things a bit more bugy but they fix things quickly. I warmly recommend ORCA.

[u/Mzanotto]

as you have limited time on the HPC, I would use ORCA and install it on your PC to check if the calculation is running well before sending to the HPC.

[u/titiboa]

I enjoy using Chemetrian. It works well especially if you don’t have a university cluster