[molpro-user] Bug in calculation of expactation value of the potential energy operator (POT)

Evgeniy Gromov Evgeniy.Gromov at pci.uni-heidelberg.de
Thu Mar 26 08:51:23 GMT 2009

Dear Gerald,

Thanks for your response. Yet could you please
give the expression for the potential energy operator
(POT) used to get the expectation value (if you know).

Best regards,

Gerald Knizia wrote:
> On Wednesday 25 March 2009 16:02, Evgeniy Gromov wrote:
>> Dear Developers and Users of Molpro,
>> There seems to be bug in calculation of expectation
>> value of the potential energy operator (POT). The
>> value I get is not equal to <E_total>-<E_kinetic>.
>> I mean it should be
>> <E_potential>=<E_total>-<E_kinetic>
>> shouldn't it?
> There are still the nuclear repulsion energy and the two electron repulsion 
> energy. The total energy is:
> 	E_tot = <t> + <v_nuc> + E_nuc + <2e-terms>
> where:
> 	t is the electronic kinetic energy
> 	v_nuc is the energy due to the interaction of the atom cores
> 		with the electrons
> 	E_nuc = \sum_{a,b!=a} Z_a Z_b/||R_a-R_b|| is the electrostatic
> 		repulsion of the atom cores amongst themselves.
> 	2e-terms is the energy due to the interaction of the electrons with
> 		each other
> For RHF, the 2e-terms are again given by j + k, which are effective 1-particle 
> operators representing the mean field Coulomb potential due to the electrons 
> and Pauli repulsion (k=exchange operator). For general theories these 
> 2e-terms look more complicated would require the 2-RDM for an exact 
> evaluation as general property expectation value.

Dr. Evgeniy Gromov
Theoretische Chemie
Physikalisch-Chemisches Institut
Im Neuenheimer Feld 229
D-69120 Heidelberg

Telefon: +49/(0)6221/545263
Fax: +49/(0)6221/545221
E-mail: evgeniy at pci.uni-heidelberg.de

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