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<TT>Gurpreet Singh wrote:</TT><BR>
<TT><FONT COLOR="#737373">> Dear Gromacs Users,</FONT></TT><BR>
<TT><FONT COLOR="#737373">> </FONT></TT><BR>
<TT><FONT COLOR="#737373">> I am using g_sas program of gromacs to calculate SASA, ?using -pbc flag.</FONT></TT><BR>
<TT><FONT COLOR="#737373">> It seems to me that the program does not take into account the periodic</FONT></TT><BR>
<TT><FONT COLOR="#737373">> boundary conditions.</FONT></TT><BR>
<TT><FONT COLOR="#737373">> Even thought this problem is mentioned in the mailing list, it still not</FONT></TT><BR>
<TT><FONT COLOR="#737373">> clear whether the program can or cannot take into account the</FONT></TT><BR>
<TT><FONT COLOR="#737373">> periodicity. </FONT></TT><BR>
<TT><FONT COLOR="#737373">> i am using gromacs3.3.2 . Could anyone please clarify this. </FONT></TT><BR>
<TT><FONT COLOR="#737373">> </FONT></TT><BR>
<BR>
<BR>
<TT><A HREF="http://bugzilla.gromacs.org/show_bug.cgi?id=180">http://bugzilla.gromacs.org/show_bug.cgi?id=180</A></TT><BR>
<BR>
I downloaded the gromacs 3.3.3 and carried out some test calculations. The PBC is still not working, at least with test i have performed.<BR>
I generated a trajcetory file containing two atoms in a cubic box of 4nm having same x and y coordinates and varied the z coordinates of one of the atoms.<BR>
one atom is fixed at z coordinate of 3.9. The result of sasa vs coordinates is as follows:<BR>
<BR>
Step no z coordinate total_sasa<BR>
1 2.05000000074506 14.1497<BR>
2 2.10000000149012 14.1497<BR>
3 2.15000000223517 14.1497<BR>
4 2.20000000298023 14.1497<BR>
5 2.25000000372529 14.1497<BR>
6 2.30000000447035 14.1497<BR>
7 2.35000000521541 14.1497<BR>
8 2.40000000596046 14.1497<BR>
9 2.45000000670552 14.1497<BR>
10 2.50000000745058 14.1497<BR>
11 2.55000000819564 14.1497<BR>
12 2.60000000894070 14.1497<BR>
13 2.65000000968575 14.1497<BR>
14 2.70000001043081 14.1497<BR>
15 2.75000001117587 14.1497<BR>
16 2.80000001192093 14.1497<BR>
17 2.85000001266599 14.1497<BR>
18 2.90000001341105 14.1497<BR>
19 2.95000001415610 14.1497<BR>
20 3.00000001490116 14.1497<BR>
21 3.05000001564622 14.1497<BR>
22 3.10000001639128 14.1497<BR>
23 3.15000001713634 14.1497<BR>
24 3.20000001788139 14.1497<BR>
25 3.25000001862645 14.1497<BR>
26 3.30000001937151 14.1497<BR>
27 3.35000002011657 13.7971<BR>
28 3.40000002086163 13.1359<BR>
29 3.45000002160668 12.5849<BR>
30 3.50000002235174 11.9237<BR>
31 3.55000002309680 11.3727<BR>
32 3.60000002384186 10.7115<BR>
33 3.65000002458692 10.1605<BR>
34 3.70000002533197 9.49926<BR>
35 3.75000002607703 8.94826<BR>
36 3.80000002682209 8.39726<BR>
37 3.85000002756715 7.51566<BR>
38 3.90000002831221 14.1497<BR>
39 3.95000002905726 7.51566<BR>
40 2.980232238769531E-008 14.1497<BR>
41 5.000003054738045E-002 14.1497<BR>
42 0.100000031292439 14.1497<BR>
43 0.150000032037497 14.1497<BR>
44 0.200000032782555 14.1497<BR>
45 0.250000033527613 14.1497<BR>
46 0.300000034272671 14.1497<BR>
47 0.350000035017729 14.1497<BR>
48 0.400000035762787 14.1497<BR>
49 0.450000036507845 14.1497<BR>
50 0.500000037252903 14.1497<BR>
51 0.550000037997961 14.1497<BR>
52 0.600000038743019 14.1497<BR>
53 0.650000039488077 14.1497<BR>
54 0.700000040233135 14.1497<BR>
55 0.750000040978193 14.1497<BR>
<BR>
<BR>
</BLOCKQUOTE>
I used the following command to calculate the sasa<BR>
g_sas_d -f test.xtc -s topol.tpr -pbc -ndots 500 <BR>
<BR>
I can attached the tpr and xtc file if needed<BR>
<BR>
With Regards,<BR>
Gurpreet singh<BR>
<BR>
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