Editing Semi-grand ensembles
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== General features == | |||
Semi-grand ensembles are used in Monte Carlo simulation of mixtures. | |||
In these ensembles the total number of molecules is fixed, but the composition can change. | |||
== Canonical ensemble: fixed volume, temperature and number(s) of molecules == | == Canonical ensemble: fixed volume, temperature and number(s) of molecules == | ||
We shall consider a system consisting of ''c'' components;. | We shall consider a system consisting of ''c'' components;. | ||
In the [[Canonical ensemble|canonical ensemble]], the differential | In the [[Canonical ensemble|canonical ensemble]], the differential | ||
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*<math> A </math> is the [[Helmholtz energy function]] | *<math> A </math> is the [[Helmholtz energy function]] | ||
*<math> \beta | *<math> \beta \equiv 1/k_B T </math> | ||
*<math> k_B</math> is the [[Boltzmann constant]] | *<math> k_B</math> is the [[Boltzmann constant]] | ||
*<math> T </math> is the | *<math> T </math> is the [[absolute temperature]] | ||
*<math> E </math> is the [[internal energy]] | *<math> E </math> is the [[internal energy]] | ||
*<math> p </math> is the [[pressure]] | *<math> p </math> is the [[pressure]] | ||
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: <math> d \left( \beta A \right) = E d \beta - (\beta p) d V + \beta \mu_1 d N - \beta \mu_1 \sum_{i=2}^c d N_i + \sum_{i=2}^c \beta \ | : <math> d \left( \beta A \right) = E d \beta - (\beta p) d V + \beta \mu_1 d N - \beta \mu_1 \sum_{i=2}^c d N_i + \sum_{i=2}^c \beta \mu_2 d N_2; </math> | ||
: <math> d \left( \beta A \right) = E d \beta - (\beta p) d V + \beta \mu_1 d N + \sum_{i=2}^c \beta (\ | : <math> d \left( \beta A \right) = E d \beta - (\beta p) d V + \beta \mu_1 d N + \sum_{i=2}^c \beta (\mu_2-\mu_i) d N_i; </math> | ||
or, | or, | ||
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where <math> \left. \mu_{i1} \equiv \mu_i - \mu_1 \right. </math>. | where <math> \left. \mu_{i1} \equiv \mu_i - \mu_1 \right. </math>. | ||
* Now considering the | * Now considering the [[thermodynamical potential]]: <math> \beta A - \sum_{i=2}^c \left( N_i \beta \mu_{i1} \right) </math> | ||
:<math> d \left[ \beta A - \sum_{i=2}^c ( \beta \mu_{i1} N_i ) \right] = E d \beta - \left( \beta p \right) d V + \beta \mu_{1} d N - | :<math> d \left[ \beta A - \sum_{i=2}^c ( \beta \mu_{i1} N_i ) \right] = E d \beta - \left( \beta p \right) d V + \beta \mu_{1} d N - N_2 d \left( \beta \mu_{21} \right). | ||
</math> | </math> | ||
== Fixed pressure and temperature == | == Fixed pressure and temperature == | ||
In the [[ | In the [[Isothermal-Isobaric ensemble]]: <math> (N_1,N_2, \cdots, N_c, p, T) </math> one can write: | ||
<math> d (\beta G) = E d \beta + V d (\beta p) + \sum_{i=1}^c \left( \beta \mu_i \right) d N_i </math> | |||
where: | where: | ||
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:<math> \beta G (\beta,\beta p, N_1, N_2, \cdots N_c ) \rightarrow \beta \Phi (\beta, \beta p, N, \beta \mu_{21}, \cdots, \beta \mu_{c1} ) </math>, | :<math> \beta G (\beta,\beta p, N_1, N_2, \cdots N_c ) \rightarrow \beta \Phi (\beta, \beta p, N, \beta \mu_{21}, \cdots, \beta \mu_{c1} ) </math>, | ||
where the ''new'' | where the ''new'' thermodynamical Potential <math> \beta \Phi </math> is given by: | ||
:<math> d (\beta \Phi) = d \left[ \beta G - \sum_{i=2}^c (\beta \mu_{i1} N_i ) \right] = E d \beta + V d (\beta p) + \beta \mu_1 d N | :<math> d (\beta \Phi) = d \left[ \beta G - \sum_{i=2}^c (\beta \mu_{i1} N_i ) \right] = E d \beta + V d (\beta p) + \beta \mu_1 d N | ||
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</math> | </math> | ||
== Fixed pressure and temperature: Semi-grand ensemble: | == Fixed pressure and temperature: Semi-grand ensemble: Partition function == | ||
TO BE CONTINUED SOON | |||