PhreeqcUsers Discussion Forum

Databases => Selecting and Modifying Databases => Topic started by: segorucu on November 24, 2015, 06:39:24 PM

Title: Pitzer Coefficients Database
Post by: segorucu on November 24, 2015, 06:39:24 PM
Hello,

I am trying to create a database for Pitzer coefficients. I wanted to ask if there is any publicly available database for the Pitzer coefficients. Is PHREEQC getting its Pitzer coefficient database from EQ3/6? Would your or their data be publicly available?

Best regards,

Emre
Title: Re: Pitzer Coefficients Database
Post by: dlparkhurst on November 24, 2015, 07:07:01 PM
There is a pitzer.dat database distributed with PHREEQC. The data comes mostly from a compilation by Niel Plummer described in the documentation for the program PHRQPITZ. Tony Appelo has made recent modifications to pitzer.dat (included in current distribution) to account better for temperature and pressure, and to add silica.
Title: Re: Pitzer Coefficients Database
Post by: segorucu on November 24, 2015, 08:42:22 PM
Hello,

I have installed the software and found the Pitzer.dat file. A lot of the data is publicly available from other sources. However, I wanted to ask if I can copy paste this data to create my own database. The database would be used in a different commercial software package. Please let me know.

Best regards,

Emre
Title: Re: Pitzer Coefficients Database
Post by: dlparkhurst on November 24, 2015, 09:03:32 PM
There are no copyrights on our software products. We ask that you give proper citation of any material that you use.
Title: Re: Pitzer Coefficients Database
Post by: segorucu on November 24, 2015, 09:07:50 PM
Thank you very much for note.

Best regards,

Emre
Title: Re: Pitzer Coefficients Database
Post by: segorucu on December 07, 2015, 05:37:50 PM
Dear Parkhurst,

In the database for Pitzer, there are 4 or 5 coefficients. I was able to find the equation for when there are 5 coefficients. Is it possible to let me know the equation when there are 4 coefficients? Is it the same as in EQ3.6? The equation they use is

x(T) = a1 + a2*(1/T - 1/298.15) + a3*ln(T/298.15) + a4*(T - 298.15)

where T is in K and hence the equation would be x(T) = a1 at T = 25C.

Thank you very much for your reply beforehand.

Best regards,

Emre
Title: Re: Pitzer Coefficients Database
Post by: dlparkhurst on December 07, 2015, 10:14:21 PM
The equation is given in the documentation for the PITZER keyword data block.

If less than six parameters are defined, the undefined parameters are assumed to be zero.