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MayukhMajumder

Member

Registered: 2021-02-23

Posts: 2

CDFT

Can you please tell me what is the physical interpretation of local softness, electrophilicity and fukui function? And what does Shanon entropy signifies?

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,468

Website

Re: CDFT

These concepts are well documented in many review articles of CDFT, see
Acta Phys. -Chim. Sin., 25, 590-600 (2009)
Chem. Rev., 111, PR43 (2011)
Chem. Rev., 103, 1793-1873 (2003)

Regarding Shanon entropy, see recent reviews
Acta Phys. -Chim. Sin., 32, 98 (2016) DOI: 10.3866/PKU.WHXB201510302
WIREs Comput Mol Sci., e1461 (2019) DOI: 10.1002/wcms.1461

MayukhMajumder

Member

Registered: 2021-02-23

Posts: 2

Re: CDFT

Thanks a lot sir! Those were helpful.
Would you please let me know if there is a method available for computing the pKb values of inorganic bases like K2CO3 or K3PO4 theoretically ? Thanks in advance!

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,468

Website

Re: CDFT

For example, to calculate pKb of K2CO3, you need to manually evaluate variation of free energy of this process:
[CO3]2- + H2O -> [HCO3]- + OH-
or alternatively, calculate variation of free energy of this process (deltaG)
[HCO3]- -> H+ + [CO3]2-
Then pKa = -RTln(Ka) = deltaG /(2.303RT)
pKa can be convert to pKb via Kw = Ka x Kb, with Kw being ion constant for water.

Reliably calculate pKa is not easy, mostly because accurate evaluation of solvation free energy of ions is difficult (not only implicit solvation model is needed, but also sometimes consideration of explicit solvent molecules is important). There are numerous papers discussing how to calculate pKa reasonably, see e.g.
J. Chem. Theory Comput., 15, 6025 (2019)
J. Phys. Chem. A, 123, 7430 (2019)