This question is more about the maths than the physics.(adsbygoogle = window.adsbygoogle || []).push({});

So I am reading the textbook by Bergersen and Plischke, and they get the following:

$$m= \tanh [ \beta (qJm+h)]$$

where ##m## is the magnetization, ##q## is the number of nearest neighbours of site ##0##, ##J## and ##h##are the coefficients in the Hamiltonian: ##H = -J\sum_{<ij>} \sigma_i \sigma_j -h \sum_i \sigma_i##;

For the question, they write that ##m(h,T) ## satisfies: ##m(h,T) = -m(-h,T)##;

but I tried to showed this and I didn't succeed.

Here's my attempt:

$$-m(-h,T) = -\tanh [ \beta(-qJm(-h,T)-h) ] = m(-h,T)$$

I used the fact that ##\tanh(-x) = -\tanh(x)##.

Am I wrong?

Did they mean something else here?

Thanks.

**Physics Forums - The Fusion of Science and Community**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# I Weiss molecular field theory

Have something to add?

Draft saved
Draft deleted

Loading...

Similar Threads - Weiss molecular field | Date |
---|---|

B Molecular Vibration of Solids | Dec 5, 2017 |

I Rotational Spectra | Nov 17, 2017 |

What can be found in the MT curves of superconductors? | Jan 28, 2015 |

Curie-Weiss law and paramagnetic materials | Jun 21, 2013 |

Deviation from Curie-Weiss law in magnetic susceptibility | Feb 8, 2011 |

**Physics Forums - The Fusion of Science and Community**