<div dir="ltr">Maybe wise thing to do is to check force field first, maybe you have some mistake in definition of force field.<div>Try to take just few atoms and check how energy evolves. If the potential is wrong you will get strange values.<br><br></div><div>Josip</div></div><div class="gmail_extra"><br><div class="gmail_quote">2018-05-03 14:12 GMT+02:00 <span dir="ltr"><<a href="mailto:4985...@qq.com" target="_blank">4985...@qq.com</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Hello, Josip, thanks very much for the answer. The system is bulk. 10s is too long to simulate, maybe build the initial configuration based on the experimental density in random way is a good choice. However, I also encountered a problem in that way, the pre-equilibriumed system is a little larger than the experimental density evaluated volume. So in avoid to the error of '<span style="font-weight:700">GEOMETRY wrong or EMAX_SPLINE too small!',</span> I set the cell abc accoording to the pre-equilibriumed volume. With the time accumulating, I found the volume expanded in NVT ensemble which is ridiculous and holes began to form in the bulk. I don't know what caused this.<br><br>在 2018年5月3日星期四 UTC+8下午3:33:29，Josip Lovrić写道：<blockquote class="gmail_quote" style="margin:0;margin-left:0.8ex;border-left:1px #ccc solid;padding-left:1ex"><span class=""><div dir="ltr">Normaly, phase transitions are hard to reproduce. You are not first one to be frustrated. Secondly 100 ps is way to short, you need to go at least to 10s of ns and maybe if you are lucky you will see some melting. Also, do you have slab or bulk?<div><br></div><div>Josip</div><div>Greetings from Gothenburg</div></div></span><div><br><div class="gmail_quote"><div><div class="h5">2018-05-03 2:37 GMT+02:00 <span dir="ltr"><<a rel="nofollow">498...@qq.com</a>></span>:<br></div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="h5"><div dir="ltr"><div>Hello, everyone, I recently want simulated the melting structure of molten salts. The simulation begin with the crystal structure and intend to be melt at 3000 K in NPT ensemble， but the result is frustrating. After 100 ps runs, the ions still in crystal structure. The parameters in the force field is in published paper and widely used, so I wonder maybe I write something of the input wrong. The input file is listed below, pls help out the dilemma, thanks very much.</div><div><br></div><div><br></div><div>&GLOBAL ! Section with general information regarding which kind of simulation to perform an parameters for the whole PROGRAM</div><div> PROJECT C6 ! Name of the project. This word will appear as part of a name of all ouput files (except main ouput file, specified with -o option)</div><div> RUN_TYPE MD ! Molecular Dynamics</div><div> PRINT_LEVEL low</div><div>&END GLOBAL</div><div><br></div><div><br></div><div>&FORCE_EVAL<span style="white-space:pre-wrap"> </span>! This section defines method for calculating energy and forces</div><div> METHOD FIST<span style="white-space:pre-wrap"> </span>! Using Molecular Mechanics</div><div> STRESS_TENSOR NUMERICAL</div><div> &MM</div><div> &FORCEFIELD<span style="white-space:pre-wrap"> </span>! This section specifies forcefield parameters</div><div> ..........</div><div> &END FORCEFIELD</div><div> &POISSON<span style="white-space:pre-wrap"> </span>! This section specifies parameters for the Poisson solver</div><div> &EWALD<span style="white-space:pre-wrap"> </span>! This section specifies parameters for the EWALD summation method (for the electrostatics)</div><div> EWALD_TYPE none<span style="white-space:pre-wrap"> </span>! Standard real-space coulomb potential is computed together with the non-bonded contributions.</div><div> &END EWALD</div><div> &END POISSON</div><div><span style="white-space:pre-wrap"> </span>&NEIGHBOR_LISTS</div><div><span style="white-space:pre-wrap"> </span> GEO_CHECK TRUE</div><div><span style="white-space:pre-wrap"> </span> NEIGHBOR_LISTS_FROM_SCRATCH TRUE</div><div><span style="white-space:pre-wrap"> </span> VERLET_SKIN 1</div><div> &END NEIGHBOR_LISTS </div><div> &END MM</div><div> &SUBSYS<span style="white-space:pre-wrap"> </span>! This section defines the system</div><div> &CELL<span style="white-space:pre-wrap"> </span>! Unit cell set up</div><div> ABC 22.56 22.56 22.56<span style="white-space:pre-wrap"> </span>! Lengths of the cell vectors A, B, and C</div><div> ALPHA_BETA_GAMMA 90.0 90.0 90.0</div><div> PERIODIC XYZ</div><div> &END CELL</div><div> &TOPOLOGY<span style="white-space:pre-wrap"> </span></div><div> COORD_FILE_NAME NaCl.xyz </div><div> COORDINATE xyz<span style="white-space:pre-wrap"> </span>! The type of the file is XYZ</div><div> &END TOPOLOGY</div><div> &END SUBSYS</div><div>&END FORCE_EVAL</div><div><br></div><div>&MOTION<span style="white-space:pre-wrap"> </span>! This section defines a set of tool connected with the motion of the nuclei.</div><div> &PRINT</div><div> &TRAJECTORY</div><div> LOG_PRINT_KEY T</div><div> FORMAT XMOL</div><div> &EACH</div><div> MD 10000</div><div> &END EACH</div><div> ADD_LAST NUMERIC </div><div> &END TRAJECTORY</div><div> &END PRINT</div><div> &MD </div><div> ENSEMBLE NPT_I</div><div> TEMPERATURE 3000</div><div><span style="white-space:pre-wrap"> </span>&BAROSTAT</div><div><span style="white-space:pre-wrap"> </span> PRESSURE 0</div><div><span style="white-space:pre-wrap"> </span> TEMPERATURE 3000</div><div><span style="white-space:pre-wrap"> </span>&END BAROSTAT</div><div><span style="white-space:pre-wrap"> </span>&THERMOSTAT</div><div> TYPE NOSE</div><div> REGION GLOBAL</div><div> &NOSE</div><div> TIMECON 100</div><div> LENGTH 3</div><div> MTS 2</div><div> &END NOSE</div><div> &END THERMOSTAT</div><div><span style="white-space:pre-wrap"> </span>TIMESTEP 1.0</div><div><span style="white-space:pre-wrap"> </span>STEPS 100000</div><div> &END MD</div><div><br></div><div> &PRINT</div><div> &RESTART</div><div> LOG_PRINT_KEY T</div><div> &EACH</div><div> MD 10000</div><div> &END EACH</div><div> ADD_LAST NUMERIC</div><div> &END RESTART</div><div> &END PRINT</div><div>&END MOTION</div><div> &END</div><div>&END MOTION</div><span><font color="#888888"><div><br></div></font></span></div></div></div><span><font color="#888888"><div><div class="h5">
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