Re: [cclib-devel] Forces from gaussian job (added feature)

[Noel O'B. <bao...@gm...>]

2009/6/12 Hugh Chaffey-Millar <hug...@ch...>:
> Hi Karol
>
>> Could I also look over your code and input/output example?
>
> Sure, I'll send these in a separate email to you only, since Noel has it
> already.
>
>> Z-matrix parsing and/or interconversion with cartesians would be useful...
>> currently I do it on a regular basis with openbabel. If not parsed, perhaps
>> a helper method could build and return the z-matrix via openbabel.
>
> That would surely be useful. Coul I quickly ask, do you use the C++ API
> directly when doing this or do you mean you convert between file formats with
> z-matrix/cartesian specifications?
>
>> For derived quantities like (second) derivatives, it will be harder to
>> maintain clarity and consistency between outputs from various programs if
>> we were to provide them potentially in both cartesian and internal
>> coordinates. I would again suggest a helper method in this case that
>> converts the standard cartesian form to internal coordinates, with a
>> Z-matrix or atom ordering given as input.
>
> Yep I suppose that would be good. When gradients are already available in
> terms of the z-matrix, I would have thought it incurs unnecessary complexity
> to invoke other methods to convert the gradients from cartesians to z-matrix.
> But in general, such infrastructure in the code would be useful.
>
> In a related project I'm currently working on, I have already written code to
> convert from forces in cartesians to forces in z-matrix, and it numerically
> differentiates the function Z(C) that returns z-matrix coordinates, Z, in
> terms of the cartesians, C, and implements the function Z using the python
> interface to openbabel.

We'd like this sort of code.

>> > As I may have mentioned, I will probably add support for a number of
>> > other programs, such as GAMESS, NWChem and possibly VASP, at some point,
>> > so obviously should do this in a style that is consistent with the rest
>> > of cclib.
>>
>> We don't parse nwchem or VASP output files at the moment, so there is no
>> parse to currently add code to for those programs.
>
> Well if I were to write some code to parse them, would you want to add it to
> cclib?

Absolutely. The only requirement is that the parser implements enough
functionality to pass the test framework.

> Cheers
> Hugh
>
>
>