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IRIS999

铁虫 (正式写手)

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专业: 应用高分子化学与物理

[求助] 请问Forcite中的Geometry Optimization能量下降很少是为什么？

MS8.0计算有机小分子的溶解度参数，单个分子用Dmol3优化之后用AC建立Cell，之后先对Cell用Forcite几何优化，但是能量总是降不下来。文献中一般建议5000步，我的跑了两万步能量还是两千多，大家能帮忙看看是为什么吗？
---- Geometry optimization parameters ----

Algorithm                      : Smart
Convergence tolerance:
  Energy                      : 2e-005 kcal/mol
  Force                      : 0.001 kcal/mol/A
  Stress                      : 0.001 GPa
  Displacement                : 1e-005 A
Maximum number of iterations : 5000000
External pressure             : 0 GPa
Motion groups rigid          : NO
Optimize cell                : NO

---- Energy parameters ----

Forcefield                   : COMPASS (Version 2.8)
Charges                      : Forcefield assigned
Electrostatic terms:
  Summation method             : Group based
  Cutoff distance             : 18.5 A
  Spline width                : 1 A
  Buffer width                : 0.5 A

van der Waals terms:
  Summation method             : Group based
  Cutoff distance             : 18.5 A
  Spline width                : 1 A
  Long range correction       : YES
  Buffer width                : 0.5 A

Energy contributors using automatic parameters:
Angle Bend                : (o1= p4= c3a)

---- Initial structure ----

Total enthalpy                : 4456.204302 kcal/mol
  External pressure term       : 0.000000 kcal/mol

Total energy                   :       4456.204302 kcal/mol

Contributions to total energy (kcal/mol):
  Valence energy (diag. terms)  :       1765.821
Bond                      :       396.975
Angle                      :       352.486
Torsion                   :       1003.879
Inversion                :       12.481
  Valence energy (cross terms)  :       -196.813
Stretch-Stretch          :       27.757
Stretch-Bend-Stretch       :       -40.342
Stretch-Torsion-Stretch    :       -32.493
Separated-Stretch-Stretch :       19.501
Torsion-Stretch          :       -520.682
Bend-Bend                :          0.000
Torsion-Bend-Bend          :          1.727
Bend-Torsion-Bend          :       347.719
  Non-bond energy             :       2887.196
van der Waals             :       281.464
Long range correction    :       -14.961
Electrostatic             :       2620.693

rms force  : 1.613E+000 kcal/mol/A
max force  : 3.320E+001 kcal/mol/A

Cell parameters: a:  28.479100 A b:  28.479100 A c:  28.479100 A
            alpha:  90.000 deg  beta:  90.000 deg gamma:  90.000 deg

---- Final structure ----

Total enthalpy                : 2860.041253 kcal/mol
  External pressure term       : 0.000000 kcal/mol

Total energy                   :       2860.041253 kcal/mol

Contributions to total energy (kcal/mol):
  Valence energy (diag. terms)  :       1157.380
Bond                      :       196.160
Angle                      :       137.849
Torsion                   :       822.769
Inversion                :          0.602
  Valence energy (cross terms)  :       -128.973
Stretch-Stretch          :       21.173
Stretch-Bend-Stretch       :       -37.436
Stretch-Torsion-Stretch    :       -34.905
Separated-Stretch-Stretch :       15.592
Torsion-Stretch          :       -459.184
Bend-Bend                :          0.000
Torsion-Bend-Bend          :          2.227
Bend-Torsion-Bend          :       363.561
  Non-bond energy             :       1831.634
van der Waals             :       -651.463
Long range correction    :       -14.961
Electrostatic             :       2498.058

rms force  : 8.778E-005 kcal/mol/A
max force  : 6.515E-004 kcal/mol/A

Cell parameters: a:  28.479100 A b:  28.479100 A c:  28.479100 A
            alpha:  90.000 deg  beta:  90.000 deg gamma:  90.000 deg

Task terminated             : Tue Feb 21 21:02:13 2017
Total CPU time used by Forcite: 23:38 minutes (1418.22s)

Termination status : Normal

TPPO Energies.jpg

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