Hi Dear LAMMPS people,
I am a beginner in LAMMPS. I want to simulate the diffusion of N2 gas through kind of zeolite that the framework is rigid. My structure contains 16 nitrogen molecule in zeolite. First of all I do a simulation in NVT ensemble to equilibrate my system. I obtain positive total energy, however the interaction energy is negative. I am confusing about positive total energy.
- when I use Ewald technique (I have cation in my zeolite structure), both total energy and interaction energy are positive. I don not know what is wrong. May I have your help. I will attached my input files, and I hope this be helpful .
Thanks in advance,
Bahareh Bamdad
in.lilsx-ewald (1.98 KB)
in.lilsx-noewald (1.83 KB)
Hi Dear LAMMPS people,
I am a beginner in LAMMPS. I want to simulate the diffusion of N2 gas
through kind of zeolite that the framework is rigid. My structure contains
16 nitrogen molecule in zeolite. First of all I do a simulation in NVT
ensemble to equilibrate my system. I obtain positive total energy, however
the interaction energy is negative. I am confusing about positive total
energy.
the absolute value of the total energy has very little meaning in MD.
what matters are that the forces are correct.
2. when I use Ewald technique (I have cation in my zeolite structure), both
total energy and interaction energy are positive. I don not know what is
wrong. May I have your help. I will attached my input files, and I hope this
be helpful .
if you apply ewald summation to a system with a charged unit cell, you
have essentially a divergent total energy. such a system in real life
would immediately explode. in the computer, you can ignore the
divergent term and thus artificially compensate that total charge. yet
under these circumstances, the total energy has even less meaning, and
even your forces may be significantly tainted, the larger the excess
charge per unit cell is compared to the volume.
axel.