# Generating orbital files with TURBOMOLE

1. Jun 29, 2010

### Morberticus

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. Jun 29, 2010

### alxm

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 ($$de^{-\alpha r^2}$$) 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 ($$\alpha$$) followed by the contraction coefficient ($$d$$).
Note that these are unnormalized values. Otherwise it's fairly straightforward.

3. Jun 29, 2010

### Morberticus

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.

4. Jun 30, 2010

### alxm

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!

5. Jul 1, 2010

### Morberticus

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.

6. Jul 1, 2010

### alxm

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.