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This keyword data block is used to specify explicitly which solution, exchange assemblage, pure-phase assemblage, solid-solution assemblage, and surface assemblage are to be used in the batch-reaction calculation of a simulation. USE can also specify previously defined kinetically controlled reactions ( KINETICS data block), reaction parameters ( REACTION data block), reaction-temperature parameters ( REACTION_TEMPERATURE data block), and mixing parameters ( MIX data block) to be used in a batch-reaction calculation.

Example data block

Line 0a: USE equilibrium_phases none 
Line 0b: USE exchange 2
Line 0c: USE gas_phase 3
Line 0d: USE kinetics 1
Line 0e: USE mix 1
Line 0f: USE reaction 2
Line 0g: USE reaction_temperature 1
Line 0h: USE solid_solution 6
Line 0i: USE solution 1
Line 0j: USE surface 1


Line 0: USE keyword , ( number or none)

USE is the keyword for the data block.

keyword --One of ten keywords, equilibrium_phases, exchange, gas_phase, kinetics, mix, reaction, reaction_temperature, solid_solutions, solution, or surface.

number --Positive integer associated with previously defined composition or reaction parameters.

none--No data of the type of the specified keyword will be used in the batch-reaction calculation.


Batch-reactions are defined by allowing a solution or mixture of solutions to come to equilibrium with one or more of the following entities: an exchange assemblage, a pure-phase assemblage, a solid-solution assemblage, a surface assemblage, or a gas phase. In addition, kinetically controlled reactions, fixed-stoichiometry reactions, and reaction temperatures can be specified for batch-reaction calculations.

Entities can be defined implicitly: a solution or mixture ( SOLUTION or MIX keywords) must be defined within the simulation, then the first of each kind of entity defined in the simulation will be used to define the reaction system. Thus, the first solution (or mixture) will be brought together with the first of each of the following entities that is defined in the simulation: exchange assemblage ( EXCHANGE), gas phase ( GAS_PHASE), pure-phase assemblage ( EQUILIBRIUM_PHASES), solid-solution assemblage ( SOLID_SOLUTIONS), surface assemblage ( SURFACE); equilibrium among these entities will be calculated and maintained. Irreversible reactions may also be added implicitly to the system, and again, the first of the following entities that is defined in the simulation is added: kinetically controlled reaction ( KINETICS), stoichiometric reaction ( REACTION), and reaction temperature ( REACTION_TEMPERATURE).

Entities to be included in the system can be defined explicitly with the USE keyword. Any combination of USE keyword number data blocks can be used to define a system. " USE keyword none" can be used to eliminate an entity that was implicitly defined to be in the system. For example, if only a solution and a surface are defined in a simulation and the surface is defined to be in equilibrium with the solution, then implicitly, an additional batch-reaction calculation will be made to equilibrate the solution with the surface. Though not incorrect, the batch-reaction calculation will produce the same compositions for the solution and surface as previously defined. By including " USE solution none", the batch-reaction calculation will be eliminated.

The composition of the solution, exchange assemblage, solid-solution assemblage, surface assemblage, pure-phase assemblage, or gas phase can be saved after a set of batch-reaction calculations with the SAVE keyword.

Example problems

The keyword USE is used in example problems 3, 6, 7, 8, 10, and 14.

Related keywords


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