Simulating an Infrared Spectrum - IR Spectroscopy on your PC using ORCA (Part 1)

[@g.bontempi691]

this is awesome! I just tried it out. I'm definitely gonna stick around for the rest of the series, thank you.

[@jakobkienke5377]

An FYI for more recent viewers of this guide: I could for the love of me not get Orca version 6.0.0 to work. But with Orca version 4.2.1, like Ben uses in the video, there were no problems at all. So if you're having trouble with getting an output file, maybe try the an other version of Orca.

[@franzmeier4472]

Two notes: - I am 99 % sure that its ok to save as txt. If you type in the extension (.inp) when specifying the file name, it will still say water.inp when saved. It's all plaintext anyways and so it shouldn't make a difference. - Pro Tip: You dont need to open cmd through windows start and then navigate to your folder of choice. Just Click the Folder Path in the Explorer Window "(This PC > DATA(C:) > OrcaCalculations > Water)", type in cmd and press enter. The terminal with the current directory applied will open automatically. Unless you included that stuff for newbies to they learn how to use the "cd" command.

[@DrBenChem]

Thanks! Although it will say "orca.inp", some versions of Windows will add the .txt extension anyway, so the full filename will be "orca.inp.txt" - which will have implications for submitting the job even if it can be read by ORCA, which I admit I'm not sure of. The protip is helpful, but I love an excuse to get people use a few more console commands, you caught me! 🫣

[@kevinender5409]

THX so much bro, i got it!! I just followed the steps and made it👍

[@CHESankariP]

Sir, I don't know how to Install orca software, would you guide me? Greetings from India🙏

[@ummatilawan5797]

Very interesting and informative, Thank you so much. My question is can we calculate the IR of a metal membrane like Pd?

[@DrBenChem]

Hi! You can absolutely calculate the IR spectrum of metal complexes, but because they have a lot more electrons, it will take a lot longer, days or even weeks!

[@jrzero]

Thank you Dr.Ben!Your video is truly helpful to me as a complete beginner in computational chemistry. Is it possible for you to make a video for CO2? I followed your method in this video and I got the IR spectrum for CO2 but I noticed the higher frequency that I obtained is 2516.98cm-1, which is quite far away from the literature value. So I am confused about which one should be the right one?

[@DrBenChem]

The experimental value is always 'right'. If your calculated value is different, remember that you are technically stimulating at zero Kelvin and at zero pressure. sites.google.com/site/orcainputlibrary/ Try the above link to try different methods and basis sets yourself and see how your results vary!

[@jrzero]

@@DrBenChem Thank you for your reply. Another one more question is could you recommend any reference books for a complete beginner like me to familiarize myself with computational chemistry for material science?

[@DrBenChem]

@@jrzero in all honesty, not really - I've picked up what I know from reading research papers, it's the best way to stay current and up to date.

[@jrzero]

@@DrBenChem Thank you. Looking forward to your next video =)

[@irvingmarquez1106]

Thanks so much for sharing

[@hongheng4801]

Hello, I'm doing with CH2O. I follow all of the instruction but at the cmd, the result shows 'orca' is not recognized as an internal or external command, operable program or batch file. What can I do?

[@DrBenChem]

Hi! You need to have installed ORCA, by downloading the latest version from the forum and running the installer. Did you do this? If you've done this, you might need to manually "add ORCA to PATH" - let me know if you if you need advice on how to do this.

[@rishikurup3906]

Yes sir how to add​@@DrBenChem

[@rishikurup3906]

​@DrBenChemyes sir how to do it

[@rishikurup3906]

Sir when i typed orca pyridyl1.inp>pyridyl1.out....the process completed within seconds and the.out file does not showed any values

[@DrBenChem]

@@rishikurup3906 Hi! What does the last line of pyridyl1.out say? Usually there's an error message that will let you know what you need to change in the .inp file to complete the calculations.

[@rishikurup3906]

@@DrBenChem Its all sorted sir. Thank you

[@motivationaljz2245]

Thank you so much. Highly appreciated. Why you are mostly using PBEo basis set? Can we use it for large organic molecules like PDI to calculate their IR?

[@DrBenChem]

What do you mean by PDI? Yes, the PBE0 basis set is a good starting point and it can be used to predict IR spectra, but it's always worth checking to see what basis sets and methods people have used with similar systems.

[@motivationaljz2245]

@@DrBenChem thank you Sir, PDI means Perylene diimide. Okay got it.

[@aminnaifar4442]

thaks you very much could you show us to do the same simulation but with benzene or diechlormethane instead of water Thanks in advance

[@DrBenChem]

If you follow the same steps but you draw benzene instead of water, you can do it on your own PC - all the software is free. Good luck!

[@lberesford2783]

Awesome!!!

[@baneetejas7738]

hello everyone , i have recently started to explore computational chemistry through our chemistry professor introducing us to it , i have tried to download orca 6.0.1 but am unable to extract the file , please help me with the same . it extracts all files but the installer version and shows 'error 0x80004005:unspecified error" when i try to open the installer it shows "Windows cannot complete extraction." "The destination file could not be created." Pease help me with this matter , i am very keen to explore the application.

[@DrBenChem]

@@baneetejas7738 Hi, have you downloaded all of the parts of the file? As I recall, it's a 3 part file, and it won't extract without all of them

[@baneetejas7738]

@@DrBenChemhi sir , for orca 6.0.1 there is only one file required as said on the orca forum , with the help of a third party extractor the job was done . But i started to run the commands like you have taught , when i put orca_mapspc water.out and so on….. it shows and error that cannot find keyword IR Spectrun , please help me with this ? Do i need to download the autoci parts and parallel parts too ?

[@DrBenChem]

@baneetejas7738 Hi, if it cannot find the keyword "IR spectrum" then it probably means you have omitted the "freq" keyword after "opt" in the .inp file. Amend the input file (.inp) and repeat the calculation (orca water.inp > water.out) and repeat the orca_mapspc command. Does that help?

[@harshrai9192]

Sir my graph is a straight line when I am using CAM-B3LYP or any other method it's proper for B3LYP only. plzz help me with this

[@DrBenChem]

Hi! That sounds like an interesting problem - can I suggest you post it on the ORCA forums, along with your input and output files? That way the combined expertise of the community can come together to help.

[@harshrai9192]

@@DrBenChem ok sure sir

[@harshrai9192]

@@DrBenChem Sir could you help me, where to post on Orca forum as I am unable to see the option for posting queries

[@Sergiypsm]

Do you plan a video for calculating PES?

[@DrBenChem]

Apologies for leaving this so long! Which form of photoelectron spectroscopy are you interested in?

[@lynnettegalvan8742]

Does Orca take broadening IR spectra into account or do you have to input code for it to do so?

[@DrBenChem]

By default there is no broadening, but when you export the IR spectrum using orca_mapspc you can manually define the broadening parameter. sites.google.com/site/orcainputlibrary/printing-and-visualization

[@lynnettegalvan8742]

@@DrBenChem Thank you so much!

[@ajyui847]

When I tried to run the first command it's shows an error "fatal error encountered, cannot open file " What to do?

[@DrBenChem]

What does your orca.inp file contain? Could you post it here?

[@ajyui847]

@@DrBenChem the same as you wrote !! But o have a doubt about the sign I putted after "PBE" I used zero

[@DrBenChem]

@@ajyui847 That's strange - it should be zero, so it sounds like you've written it correctly. Is the filetype correct? Is it definitely a .inp file? Notepad will default to making a .txt file, which can't be read. And is there a .xyz file also present?

[@ajyui847]

@@DrBenChem I changed the name of XYZ file , I gave it the same name as the inp , and it worked , but it still calculating ! I'm trying an organic compound that contains 35 atom ! Does it take so long ?

[@DrBenChem]

@@ajyui847 I'm glad you got it working! Yes, large structures will take a lot longer. Your options for making it faster are more or less limited to either a) using a supercomputer - if you're part of a university it is likely you have access to one or b) using a lower level of theory for a less accurate but faster result - I'd maybe try an HF-3c method.

[@mubashirriaz4104]

Can I've IR spectrum for Cyclooctatetraene?

[@DrBenChem]

I should imagine you could relatively easily simulate that spectrum, yes

[@leonardofigueiredo57]

How can we change the FWHM?

[@DrBenChem]

I think changing the -w value should do the trick

[@moulichattoraj6682]

Can i do it for Mose2?

[@DrBenChem]

Apologies, what do you mean by Mose2?

[@DrBenChem]

If you mean Molybdenum diselenide, I would recommend a different software package, perhaps VASP or CASTEP - I'm afraid I don't have very much experience in using those.

[@moulichattoraj6682]

@@DrBenChem Thank you so much for your time. I want to have vibrational modes for Molybdenum Di selenide. But ORCA is showing error like Frozen core calculation ,SCF not converged. So can I do RAMAN/IR with orca?

[@moulichattoraj6682]

@@DrBenChem Thank you so much. I need those vibrational calculation for my project

[@DrBenChem]

@@moulichattoraj6682 sorry I couldn't help directly, but I'm glad I could point you in the right direction!