[molpro-user] Lattice point of charges

[Muammar El Khatib]

Dear Molpro users,

I'm trying to use the lattice point of charges in MOLPRO, and a doubt has
raised. Maybe it is a mistake of mine, and I hope somebody could shed some
light on this.

For example, if I run the hydrogen atom using as input file the one I show
below:

--------------8<-----------------------8<---------------------------8<--------
    ***, H
    gprint,basis;
    gprint,orbital;
    gprint,civector;
    mass,print
    symmetry,x,y,z;

    geometry=
    {
     H    0,    0.0,       0.0,     0.0;
     }

    basis=6-31g**

    int;

    {hf;
    occ,1,0,0,0,0,0,0,0;
    wf,1,1,1;
    }
    put,molden,hhf.molden
    ---

--------------8<-----------------------8<---------------------------8<--------

I obtain an energy that is -0.49823291. But now, If I set the hydrogen atom as
dummy¹ (so that its charge become 0), and then I place a point of charge of "1"
at 1 bohr (0.529177249Å)[that is the most probable distance between proton and
electron in the hydrogen's ground state] I obtain an energy that is -0.33978462
(see input, and lattice file below).

--------------8<-----------------------8<---------------------------8<--------
    ***, H
    gprint,basis;
    gprint,orbital;
    gprint,civector;
    mass,print
    symmetry,x,y,z;

    geometry=
    {
     H    0,    0.0,       0.0,     0.0;
     }

    basis=6-31g**

    int;
    dummy,H;    ! I placed here so that it is not reseted by the int card.
    LATTICE,INFILE=hlattice
    {hf;
    occ,1,0,0,0,0,0,0,0;
    wf,1,1,1;
    }
    put,molden,hhf.molden

    ---

lattice file:

Point Charges
1
0.0,0.0,0.529177249,1.00,0

--------------8<-----------------------8<---------------------------8<--------

Why is this difference in the energy? After doing some tests, for "reproducing"
the energy obtained without point of charges, I found that the lattice file
should be approximately:

Point Charges
1
0.0,0.0,0.0301091,1.00,0

And thus, I obtained an energy value that is -0.49624441.

Regards,

1. http://www.molpro.net/info/current/doc/manual/node107.html

PS. I have searched a lot in the mailing list archives, and there is no much
information about it.
--
Muammar El Khatib.
Linux user: 403107.
Key fingerprint = 90B8 BFC4 4A75 B881 39A3 1440 30EB 403B 1270 29F1
http://muammar.me | http://proyectociencia.org
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