Multiwfn forum

saeed_E

Member

Registered: 2019-12-21

Posts: 237

Inconsistency between interaction energy and AIM descriptors

Dear Tian,
Please consider the XB interaction between F-I and F-Br as two LAs and the nitrogen atom of a given Diene. Values of interaction energies (through sobEDAW or DLPNO-CCSD(T)) indicate that the XB interaction between F-I and nitrogen atom is much more stronger than that between F-Br and nitrogen atom. On the other hand, the value of Rho, H, and |V|/G computed at the BCP of mentioned XB interactions (F-I...N and F-Br...N) show that the interaction between F-Br and N atom is stronger than that between F-I and N! Indeed, the values of interaction energies and AIM descriptors are quite against each other. If possible, please let me know how you explain such an inconsistency I have not ever encountered.

Please be aware that geometry optimizations were done at M06-2X/def2-TZVP level and corresponding "chk" files were used for AIM analysis by Multiwfn.

Sincerely,
Saeed

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,773

Website

Re: Inconsistency between interaction energy and AIM descriptors

Dear Saeed,

This observation is somewhat expected. If you perform ESP analysis by Multiwfn, you should find ESP over sigma-hole of iodine atom is much larger than the case of Br atom, indicating stronger electrostatic attraction interaction with the nitrogen. However, iodine atom has a much larger radius than Br, leading to sparser distribution of electron density in interaction region, thus rho(BCP) is lower.

Best,

Tian

saeed_E

Member

Registered: 2019-12-21

Posts: 237

Re: Inconsistency between interaction energy and AIM descriptors

Dear Tian,
Thank you very much.

Sincerely,
Saeed