Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Generating orbital files with TURBOMOLE

  1. Jun 29, 2010 #1
    Hi,

    This question might be a little too specific, but does anyone know how (or where I might find literature) to generate basis set files used by the program TURBOMOLE. I am attempting to fit simple gaussian orbitals to dummy atoms but no luck so far.

    Thanks
     
  2. jcsd
  3. Jun 29, 2010 #2

    alxm

    User Avatar
    Science Advisor

    No problem. (Although I'm not sure if you want to read them or write them?) The format looks like this (example is the 6-31G basis for carbon)

    Code (Text):

    $basis
    *
    c   6-31G
    *
        6  s
       3047.5249000              0.0018347        
        457.3695100              0.0140373        
        103.9486900              0.0688426        
         29.2101550              0.2321844        
          9.2866630              0.4679413        
          3.1639270              0.3623120        
        3  s
          7.8682724             -0.1193324        
          1.8812885             -0.1608542        
          0.5442493              1.1434564        
        1  s
          0.1687144              1.0000000        
        3  p
          7.8682724              0.0689991        
          1.8812885              0.3164240        
          0.5442493              0.7443083        
        1  p
          0.1687144              1.0000000        
    *
    $end
     
    So the syntax here is:
    Code (Text):

    $basis
    *
    <element> <basis set name>
    *
     <# primitive gaussians> <shell type>
     data
     <# primitive gaussians> <shell type>
     data
    *
    <element> <basis set name>
    *
     <# primitive gaussians> <shell type>
     data
    *
    $end
     
    And so forth.

    So you say how many primitive Gaussians ([tex]de^{-\alpha r^2}[/tex]) your radial function has, and s/p/d/f (and so on) to specify the angle-dependent part. And each line after has the exponent ([tex]\alpha[/tex]) followed by the contraction coefficient ([tex]d[/tex]).
    Note that these are unnormalized values. Otherwise it's fairly straightforward.
     
  4. Jun 29, 2010 #3
    Many thanks for the help. I have written a simple basis file and turbomole has accepted it.

    One last question: I have generated a couple of dummy points using turbomole's define program, and assigned them simple gaussians. It seems to be going ok, until I try and generate molecular orbitals from these dummy atoms. Normally I would do an eht calculation in turbomole's 'occupation number & molecular orbital definition' define menu, but it (rightly) tells me I have no electrons in my 'molecule' and refuses to give me a mos file. I have tried manually inserting electrons using the 'man' option, but am still unable to get molecular orbitals. Is my 'molecule' too unphysical for turbomole? Is there a step I'm missing? I notice the same thing happens when I remove nuclear charge from normal atoms like H2.

    Thanks again for the help.
     
  5. Jun 30, 2010 #4

    alxm

    User Avatar
    Science Advisor

    Well, are you saying you're trying to do a calculation without any nuclear charges anywhere? That won't work; it shouldn't even converge!

    What's your goal here?
     
  6. Jul 1, 2010 #5
    My goal is essentially to create an electron(s) that are free from any atomic nuclei, but still have a bound state (kind of like a particle in a box). It is unphysical, but I am really only interested in the type of molecular orbitals it generates (No geometry optimisation or anything like that), as it might save me some analytical legwork.

    I have generated a hydrogen atom thousands of angstroms away from my dummy atoms, and not given it a basis set, in the hope that this will force the charge onto my dummy atoms. It is horribly contrived but it might work.
     
  7. Jul 1, 2010 #6

    alxm

    User Avatar
    Science Advisor

    There aren't any molecular orbitals. Those are bound states. Without any potential you have no bound, stationary, states, meaning no solutions to the time-independent Schrödinger equation. (And the time-dependent result would simply be to disperse)

    I doubt it. The software simply wasn't meant to handle this kind of situation, and it's not always easy to get it to converge for real scenarios.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook