Advanced Options-
Click on any of the numbered circles below to open a Help topic.
Otherwise, please see the relevant text under this Advanced Options image.
Included in the "My Data" folder are several example files that can be loaded to illustrate some of the help topics listed below.
Default settings for new cases are 1e-4 for convergence criterion and 50 for iterations. Geochem assumes that the reactions occur at 25 degrees celsius and 1 atmosphere pressure.
1) Guessed pH- when Geochem will calculate the pH, the system needs a guess. Enter an approximate pH value. See also areas (10) and (2) for more on this topic. Most users will be making solutions with a known pH and will not opt for having Geochem make this calculation. See Help files on Calculating pH for a more complete treatment of this topic.
2) Total H+ - When Geochem will be calculating the pH one needs to enter the Total H+ (TOTH) in the system. See Help file on Calculating pH for a more complete treatment of this topic.
3) CO2 Partial Pressure- Enter the CO2 partial pressure (0 for closed) if the solution is regarded as being open with respect to CO2. See the Help file on CO2 gas for more information.
4) N2 Partial Pressure: Enter the N2 partial pressure; used only for redox calculations with NO3- being considered. See the Help file on Redox reactions for more information.
5) Electron Activity- : Enter the electron activity; used only for redox calculations. See also (6) and the Help file on Redox reactions for more information.
6) Redox Reactions- check off the box and enter the appropriate reaction codes. See also (5) and the Help file on Redox reactions for more information.
7) Mixed solids- check of the box and enter the mixed solids codes. See the Mixed Solids Help files for a more thorough explanation.
8) Solids- the user has the option of having no solids considered (None Allowed), precipitation (can precipitate), or allowing or disallowing specific simple solid phases (imposed phases to follow). The last option requires that the user enters specific codes to indicate what will be allowed or disallowed. Please see the Imposed / Disallowed Phases Help file for more on this topic.
9) Output Tables- Choose the type of output will be seen when a case is run. Default output tables are: Case Progress , Overall Speciation, and Primary Percentage Distribution. Please see the Output Tables help file for more information on this subject.
10) Calculate pH- allows user to have Geochem calculate the pH. See also areas (1) and (2) for more on this topic. Most users will be making solutions with a known pH and will not opt for having Geochem make this calculation. See the Help files on Calculating pH for a more complete treatment of this topic.
11) Manually Edit Guesses-Entering good guesses is relevant when one anticipates a much lower free concentration for any of the solution components.
12) Hide- allows the user to close the Advanced Options display.