Hi gmx users, <br>I have tried to simulate a box with 1000 molecules
of toluene <br>and I always have obtained a positive value for the potential energy. <br>I
have used three different models of potential (with and without
14 interactions) <br>and all of them provides a positive value for energy. I must be
falling in <br>some error or making some wrong analysis but I do not know
what. <br>Below I put the average values that I got from the
simulations that I made. <br>If somebody will be able to help me, I will be
grateful!<br>Bests<br>eef<br clear="all"><br>Two questions about these results:<br># Why are so larger the values for LJ-14?<br># How can I compose the potential energy from the components?<br>Would not be U = LJ + Coul + bond + ang + dihed ? And LJ-14?
<br><br> USING OPLS-UA with 14 interactions<br> <====== ############### ==><br> <==== A V E R A G E S ====> <br> <== ############### ======><br><br> Energies (kJ/mol)
<br> Bond Angle Improper Dih. LJ-14 Coulomb-14<br> 1.74553e+04 2.86624e+03 1.04333e+04 6.20512e+04 0.00000e+00<br> LJ (SR) Disper. corr. Coulomb (SR) Potential Kinetic En.
<br> -3.90255e+04 -4.73494e+03 2.98090e+01 4.90753e+04 2.62518e+04<br> Total Energy Temperature Pressure (bar)<br> 7.53271e+04 3.00743e+02 -3.32933e+00<br><br><br><br><br><br> USING GMX with 14 interactions
<br> <====== ############### ==><br> <==== A V E R A G E S ====> <br> <== ############### ======><br><br> Energies (kJ/mol)<br> Bond Angle Improper Dih. LJ-14 Coulomb-14
<br> 1.75692e+04 3.90052e+03 8.64676e+03 5.45622e+04 -1.01334e+02<br> LJ (SR) Disper. corr. Coulomb (SR) Potential Kinetic En.<br> -4.84750e+04 -2.16220e+03 -8.82568e+01 3.38519e+04
2.62111e+04<br> Total Energy Temperature Pressure (bar)<br> 6.00630e+04 3.00276e+02 1.23474e+00<br><br><br><br><br><br> USING OPLS-AA with 14 interactions<br> <====== ############### ==>
<br> <==== A V E R A G E S ====> <br> <== ############### ======><br><br> Energies (kJ/mol)<br> Bond Angle LJ-14 Coulomb-14 LJ (SR)<br> 2.63123e+04
2.60679e+04 4.35409e+04 -1.94043e+04 -4.08125e+04<br> Disper. corr. Coulomb (SR) Coul. recip. Potential Kinetic En.<br> -1.39923e+03 7.83183e+02 8.19773e+03 4.32861e+04 5.65749e+04<br>
Total Energy Temperature Pressure (bar)<br> 9.98610e+04 3.02436e+02 2.24669e+03 <br><br><br><br><br><br> USING OPLS-AA without 14 interactions
<br> <====== ############### ==><br> <==== A V E R A G E S ====> <br> <== ############### ======><br><br> Energies (kJ/mol)<br> Bond Angle LJ (SR) Disper. corr. Coulomb (SR)
<br> 2.02244e+04 2.43199e+04 -4.04650e+04 -1.39923e+03 1.24955e+03<br> Coul. recip. Potential Kinetic En. Total Energy Temperature<br> 8.38794e+03 1.23176e+04 5.56793e+04 6.79968e+04
2.97648e+02<br> Pressure (bar)<br> 1.73270e+03<br> <br>-- <br>_______________________________________
<br>Eudes Eterno Fileti<br>Centro de Ciência Naturais e Humanas<br>Universidade Federal do ABC<br>Rua Catequese, 242 - 3º Andar<br>09090-400 Santo André - SP Brasil<br>Tel: +55 11 4437-1600 ramal 408<br>skype: eefileti<br>
<a href="http://cromo.ufabc.edu.br/~fileti/">http://cromo.ufabc.edu.br/~fileti/</a>