Multiwfn forum

sayan307

Member

Registered: 2019-01-14

Posts: 38

Transition Mulliken Charge

Hi Tian,

I need to compare my TrESP coupling with the coupling from transition Mulliken charges. I know that TrESP is better but still I need to compare my results. I noticed that Multiwfn can calculate this transition Mulliken charge also, but I didn't find any example to compute them. So, could you please help how can I proceed to calculate this if I have TDM.fch or corresponding .wfn file after symmetrization of the transition density matrix(TDM.fch)...? or I need to proceed differently...?

Thanks.

Best,
Sayan

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,776

Website

Re: Transition Mulliken Charge

Dear Sayan,

Because calculation of Mulliken transition charges is so easy according to Section 3.21.12 of the manual, therefore I didn't explicitly provide example in the manual. Below is a practical example:

N-phenylpyrrole.fch
18
12
N-phenylpyrrole.out
3

Then you will find atmtrchg.chg in current folder, which records Mulliken transition charge at the last column.

You don't need to worry about symmetrization or sqrt(2) problems in this calculation process.

Best,

Tian

sayan307

Member

Registered: 2019-01-14

Posts: 38

Re: Transition Mulliken Charge

Hi Tian,

Thanks. So, here .fch file is the Gaussian formatted .chk file right...? or anything else..?

Best,
Sayan

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,776

Website

Re: Transition Mulliken Charge

Dear Sayan,

.fch denotes formatted .chk file. Of course, it is not the only choice.

Best,

Tian

sayan307

Member

Registered: 2019-01-14

Posts: 38

Re: Transition Mulliken Charge

Hi Tian,

The .molden.input from ORCA and .fchk from Gaussian have the features used as an input in Multiwfn... right....?

Also, if I can understand correctly... for the Mulliken transition charge calculation the transition density matrix needs not to be symmetrized what is essential for TrESP calculation, that's why I don't need to worry about this sqrt(2) problem.... right ...?

Best,
Sayan

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,776

Website

Re: Transition Mulliken Charge

Dear Sayan,

.molden file can provide exactly the same information for Multiwfn as .fchk. You can use .molden instead in all Multiwfn examples where .fchk is used as input file. You will understand better about this point if you read Section 2.5 of the manual.

In the calculation of Mulliken transition charge, the TDM is constructed by Multiwfn according to configuration coefficients automatically, since the TDM is correct, the sqrt(2) should not be further manually taken into account. Besides, as can be seen in the formula in Section 3.21.12, the derivation of the Mulliken transition charge implies the symmetrization during calculation, therefore you also don't need to choose whether or not symmetrizing the TDM.

Best,

Tian

sayan307

Member

Registered: 2019-01-14

Posts: 38

Re: Transition Mulliken Charge

Hi Tian,

For Mulliken transition charge calculation, is it possible to use charge restraint over a few atoms in Multiwfn just like RESP module for electrostatic potential...? Thanks.

Best,
Sayan

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,776

Website

Re: Transition Mulliken Charge

Hi Tian,

For Mulliken transition charge calculation, is it possible to use charge restraint over a few atoms in Multiwfn just like RESP module for electrostatic potential...? Thanks.

Best,
Sayan

Dear Sayan,

No, it is not possible.

Best,

Tian