[molpro-user] ump2 method in molpro is different from the one in gaussian?

[lydia]

Thanks, Kirk.
In molpro, we can change the number of core electrons in each
irreducible presentation. So maybe we can make them consistent with
each other. Do you know how the default core electrons was set in
gaussian?

lydia

On Sat, Mar 19, 2011 at 12:13 PM, Kirk Peterson <kipeters at wsu.edu> wrote:
> Dear Lydia,
>
> it looks to me that different numbers of electrons are probably being correlated in the two
> jobs.  In the case of ECP-based calculations, the default frozen core in Gaussian is often
> very different from that of Molpro.
>
> regards,
>
> Kirk
>
> On Mar 18, 2011, at 2:54 PM, lydia wrote:
>
>> Hi all,
>> I found the ump2 calculation in molpro get different energy from the
>> one of Gaussian, but they have the same UHF energies.
>>
>> This is from molpro:
>> The input file is
>> {uhf;orbprint,10;maxit,200;
>> wf,85,1,1;closed,16,10,11,5;occ,17,10,11,5;}
>> {ump2;
>> orbital,IGNORE_ERROR;
>> closed,16,10,11,5;
>> occ,17,10,11,5;
>> wf,85,1,1;}
>> and output file is
>> 1PROGRAM * UMP2 (Unrestricted open-shell)
>> Reference energy                   -1463.161083731141
>> Correlation energy                    -2.548208935082
>> !UMP2 STATE 1.4 Energy             -1465.709292666223
>>
>> This is from gaussian:
>> HF=-1463.1610804
>> MP2=-1467.12587
>>
>> Since they have the same UHF energy, the wavefunction, orbitals etc
>> are the same. The difference can only come from the correlation energy
>> calculation.
>> So I want to know the methodolody for UMP2 is different in Molpro and
>> gaussian? I checked the molpro manule and did not get any useful
>> information for that. If you have some experiences, please share with
>> me. Thanks in advance.
>>
>> lydia
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>
>