# Calculate Quantum Partition Function

• QFT25
The quantum partition function in this case can be calculated by summing over the eight possible spin configurations and taking into account the corresponding energies. Your result of 2*E^(3*J*B/4)+6*E^(-J*B/4) accounts for all eight configurations and is a valid solution.
QFT25

## Homework Statement

Consider the case when the three Ising spins are replaced by quantum spins 1/2's with a Hamiltonian

H=-J(s1.s2+s2.s3+s3.s1) calcualte the quantum partition function

## Homework Equations

Partition function is the sum of E^(-H*B) where B is 1/kt

## The Attempt at a Solution

Because this is the discrete case I'm assuming the fact that this is a quantum partition function doesn't make much of a difference. there are eight possibility, two of them are (1/2,1/2,1/2),(1/2,1/2,-1/2) and when I sum them all up I get 2*E^(3*J*B/4)+6*E^(-J*B/4). Is my approach correct or am I missing something subtle because this is quantum partition function?

Your approach and result look correct to me.

## 1. What is a quantum partition function?

A quantum partition function is a mathematical tool used in statistical mechanics to calculate the thermodynamic properties of a system consisting of particles that obey quantum mechanics. It takes into account the different energy levels and probabilities of a particle in a given system, and can be used to calculate various thermodynamic quantities such as entropy, internal energy, and free energy.

## 2. How is the quantum partition function calculated?

The quantum partition function is calculated by summing over all possible energy states of the system, taking into account the degeneracy of each state and the Boltzmann factor. This calculation can be done analytically for simple systems, or numerically using computer algorithms for more complex systems.

## 3. What is the significance of the quantum partition function?

The quantum partition function is significant because it provides a link between microscopic properties (such as energy levels) and macroscopic properties (such as temperature and pressure). It allows for the prediction of thermodynamic behavior of quantum systems, which is crucial in many fields of physics and chemistry.

## 4. Can the quantum partition function be used for all systems?

No, the quantum partition function is only applicable to systems that obey quantum mechanics. This includes particles such as atoms, molecules, and subatomic particles. It cannot be used for classical systems, which follow the laws of classical mechanics.

## 5. How does temperature affect the quantum partition function?

Temperature affects the quantum partition function through the Boltzmann factor, which takes into account the energy of a particle at a given temperature. As temperature increases, the Boltzmann factor increases, leading to a larger contribution to the partition function from higher energy states. This can change the overall thermodynamic properties of the system.

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