[CPMD-list] Reluctant hydrogen

[Erik Santiso]

Hi. Thanks for replying!

It doesn't change anything, though. I think the program realizes that automatically, in the previous output files it recognized the system as a doublet without me saying it.

This problem is driving me crazy because it is such a simple thing and it's not working. I thought that maybe it was somehow related to using OLDCODE, but it doesn't seem to be that either. I did the whole same thing using OLYP (with a Vanderbilt pp generated for this functional) and it works. The problem only happens with HCTH.

Thanks!

Erik.

> Hi,
> 
> If you include multiplicity ( 2) for the system,
> how will it work by LSD?
> 
> Regards,
> 
> Yixuan Wang
> 
> -----Original Message-----
> From: cpmd-list-admin at cpmd.org [mailto:cpmd-list-admin at cpmd.org]On
> Behalf Of Erik Santiso
> Sent: Wednesday, July 23, 2003 11:59 AM
> To: cpmd-list at cpmd.org
> Subject: [CPMD-list] Reluctant hydrogen
> 
> 
> 
> Hi everybody. I've been dealing with a strange problem and I can't seem to find where the error is. I'm trying to do a wavefunction optimization for an isolated hydrogen atom using CPMD. I'm using a Vanderbilt pseudopotential and the HCTH functional, here's my input file:
> 
> &CPMD
> 
>  OPTIMIZE WAVEFUNCTION
>  ISOLATED MOLECULE
>  MEMORY BIG
>  LSD
> 
> &END
> 
> &SYSTEM
> 
> SYMMETRY
>  1
>  CELL
>  30.0000 1.0 1.0 0.0 0.0 0.0
>  CUTOFF
>  35 
> 
> &END
> 
> &ATOMS
>   
> *001-H-ghct--leweb.uspp BINARY
>  LMAX=S
>  1 
>  10.0000   0.000000   0.0000000
> &END 
> 
> &DFT
>  
>   FUNCTIONAL HCTH 
>   GC-CUTOFF
>    5.D-5
>  
> &END
> 
> Now, for some reason the above doesn't converge. If I try a different method (e.g. PCG MINIMIZE) it converges but gives a total energy of circa -0.4, which is not right. Since I programmed the HCTH into Dr. Vanderbilt's code myself, I thought there might be an error in the pseudopotential, but I've checked it and compared it with the one in functionals.f in CPMD and they give identical results. I've tried running the same thing with other pseudopotentials and with a similar input file they converge extremely fast to about -0.5. 
> 
> There's another glitch: if I remove the LSD option from the above input, it converges very fast to an energy of about -0.46. Now the question is: shouldn't it converge to a lower value in the LSD run? I thought there was a problem with the LSD_HCTH routine in CPMD, but I couldn't find any error in it either. I'm now out of ideas on what could be wrong here, so if anyone can give me a hint on what may be failing here I'd appreciate it very much. I'm not attaching the pseudopotential file or the code I used to generate it to avoid cluttering up all your mailboxes, if anybody wants to look into it let me know and I'll send the files ASAP. Thanks a lot!
> 
> Erik.
> 
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> 
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