Different free energies for crown example

From NWChem

Viewed 1307 times, With a total of 0 Posts
Jump to: navigation, search

Clicked A Few Times
Threads 12
Posts 43
Dear everyone,

There is an example on free energy computation, crown, provided by NWchem. The input file is summarized as follows:

 start crown

prepare
system crown_setup
new_top
free
modify atom 7:Na initial type Na final type K
solvate cube
write crown_setup.rst
end

After MD equilibration, start free energy computation:

 md
system crown_ti
new forward 11 of 11
step 0.002 equil 1000 data 2000 over 2000
cutoff 0.9
isotherm 298.15 trelax 0.1 0.1
print step 100 stat 1000
update pairs 5 center 1 long 1
record rest 0 prop 10
end

The following are the results:

MULTICONFIGURATION THERMODYNAMIC INTEGRATION INCLUDING MASS CONTRIBUTIONS

Run Lambda   Free Energy
Accumulated
kJ/mol

1 0.000 -5.739
2 0.100 -42.812
3 0.200 -88.505
4 0.300 -134.737
5 0.400 -184.560
6 0.500 -237.970
7 0.600 -292.599
8 0.700 -347.419
9 0.800 -402.037
10 0.900 -457.132
11 1.000 -485.309

MULTISTEP THERMODYNAMIC PERTURBATION INCLUDING MASS CONTRIBUTIONS

Run Lambda   Accumulated 
kJ/mol

1 0.000 21.458
2 0.100 48.340
3 0.200 66.397
4 0.300 81.492
5 0.400 93.225
6 0.500 101.531
7 0.600 108.736
8 0.700 114.808
9 0.800 120.603
10 0.900 126.142
11 1.000 128.933

I want to know why the results based on THERMODYNAMIC INTEGRATION and THERMODYNAMIC PERTURBATION are different? Thanks in advance.

Jingbo


Forum >> NWChem's corner >> QMMM



Who's here now Members 0 Guests 0 Bots/Crawler 1


AWC's: 2.5.10 MediaWiki - Stand Alone Forum Extension
Forum theme style by: AWC