QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: zhangguangping on April 5, 2016, 16:03

Title: solvent effect in ATK
Post by: zhangguangping on April 5, 2016, 16:03

Dear ATK supporter,

As in the manual says it is possible to consider the solvent effect in ATK-2015.1.

"It is possible to perform calculations of solvents. In this case, the volume of the configuration is defined by inscribing each atom in a sphere with a size given by the van der Waals radius of the element. Inside the volume of the configuration the dielectric constant is 1, outside the volume of the configuration the dielectric constant is equal to the value of solvent_dielectric_constant."

Why the dielectric constant is 1 inside the volume of the configuration? I think the dielectric function inside the volume should depend on the material inside the volume of the configuration.

With best regards,

/Guangping Zhang

Title: Re: solvent effect in ATK
Post by: Anders Blom on April 5, 2016, 16:58

This is only the "free space" dielectric constant. You are of course right, that the electrons and ions will provide screening of the electrostatic fields, resulting in an effective dielectric constant that is > 1 inside the material. What this parameter gives you is the ability to define a different dielectric constant in the vacuum, where there are no atoms.

Title: Re: solvent effect in ATK
Post by: zhangguangping on April 5, 2016, 20:27

Quote from: Anders Blom on April  5, 2016, 16:58

This is only the "free space" dielectric constant. You are of course right, that the electrons and ions will provide screening of the electrostatic fields, resulting in an effective dielectric constant that is > 1 inside the material. What this parameter gives you is the ability to define a different dielectric constant in the vacuum, where there are no atoms.

Dear Anders,

Thanks for your reply.
You mean the dielectric constant 1 in the volume of the configuration is the free space between the van der Waals radius of atoms in the configuration?

With best regards,

Guangping Zhang

Title: Re: solvent effect in ATK
Post by: Anders Blom on April 5, 2016, 22:41

Sort of, yes, although inside the config the electron cloud is so delocalized that there isn't really any free space.

Title: Re: solvent effect in ATK
Post by: zhangguangping on April 6, 2016, 05:08

Quote from: Anders Blom on April  5, 2016, 22:41

Sort of, yes, although inside the config the electron cloud is so delocalized that there isn't really any free space.

Yes, that is indeed there is nearly no space with dielectric constant of 1 inside the configuration.

Thanks so much for your kind reply.

Guangping Zhang