QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: yusciky on July 18, 2014, 16:52

Title: Why there is no temperature dependance of Total Energy
Post by: yusciky on July 18, 2014, 16:52

Dear Sir:
Now I have a problem that I want to see the function of temperature on the elastic modulus of MoS2 monolayer. I have the simple orthorhombic lattice style.
So I simulated Total Energy at various temperatures of my unit cell (6 atoms) applied by different strain, 0%, -1%, 1%. But for different temperatures, their total energy are completely the same at the same strain. I tried different calculation methods (LDA, GGA, Extended Huckel, SK) but all of them gave me the same results that the Total Energy has no dependance on Temperature. But the total energy given by different methods have a big difference. What's my problem?

Title: Re: Why there is no temperature dependance of Total Energy
Post by: zh on July 19, 2014, 00:13

All the DFT calculations are performed for 0K. To including the temperature effect, one may calculate the free energy through the estimation of phonon and the quasi-harmonic approximation, or perform the molecular dynamics simulations.